Mercedes W176 A-Class 2012 –

The chassis and suspension

Agility and refined sportiness

Refined sportiness means maximum agility combined with the sense of safety, unspoilt driving stability and high levels of ride comfort which are all typical of the brand.

The suspension of the new A-Class has a four-link rear axle, electromechanical power steering with assistance functions and ESP^® with “Extended Traction Control” (XTC).

During development, the suspension experts made intensive use of simulations and the driving simulators at the Mercedes development centre in Sindelfingen as part of the so-called digital ride and handling test.

The preconditions for achieving dynamic handling are excellent in the A-Class. This is because compared with its predecessor the centre of gravity (24 mm lower) and seating position (174 mm lower) has been reduced significantly.

A new feature is the four-link rear axle: forces are absorbed by three control arms and one trailing arm per wheel. This means that longitudinal and lateral dynamics are virtually independent of one another.

Wheel carriers and spring links are made of aluminium to reduce the unsprung masses. The goal was to achieve high lateral agility with high driving stability thanks to small sideslip angle on the rear axle.

Three chassis and suspension set-ups are available: the comfort suspension and optional sports suspension for sporty yet comfortable handling (in conjunction with the Dynamic Handling package or the AMG Sport equipment line).

In addition, the A 250 Sport has a sporty, “engineered by AMG” high-performance suspension. Altogether this results in low dynamic rolling behaviour and low start-off pitch angle.

Furthermore, the vehicle also has a reduced tendency to understeer in the higher lateral acceleration range: the driver is therefore able to control changes in direction with low steering input but high steering precision.

When accelerating out of bends taken at speed, the tendency to understeer is reduced even further by “Extended Traction Control” (XTC): with this function, ESP^® provides support in the form of directional stability by generating a yaw moment on the front and rear wheels located on the inside of the bend.

Steering: mechanical with electric assistance

The electromechanical steering of the A-Class has been redesigned. The electric motor of the servo assistance system is now located directly on the steering gear as a dual pinion EPS system.

The steering system makes an important contribution to the vehicle’s overall efficiency, as the steering assist function only requires energy when steering actually takes place.

A Direct-Steer system is available in combination with the Dynamic Handling package or AMG Sport equipment line.

This provides a noticeably more direct steering ratio over the turning angle thanks to the variable ratio, and enhances the vehicle’s handling and agility substantially.

The steering conveys a high sense of safety, as the driver experiences a consistent and precise response to all steering movements.

The electric power steering also enables various steering assistance functions which are activated by the ESP^® control unit. These include

Countersteering in case of oversteering
Corrective steering when braking on road surfaces offering different levels of grip (split-fraction braking)
Mitigating the extent to which the front-wheel drive influences the steering
Compensating crosswind and road gradients
- The electric power steering also makes Active Park Assist possible.

With all engine variants, the A-Class comes with disc brakes on all wheels. The callipers on the rear axle and the brake boosters are made of aluminium.

A particularly convenient feature is the HOLD function, which is familiar from the larger model series: when stopping, for example at traffic lights, the driver merely has to press the brake pedal slightly more firmly and the brake will remain engaged until he moves off again.

The brake is released automatically when the driver steps on the accelerator. On versions with manual transmission, the Hill Hold function automatically prevents the vehicle from rolling back unintentionally when starting on a slope.

The A-Class is equipped with an electric parking brake, which operates by means of actuator motors acting on the callipers of the rear axle.

The parking brake is activated via a button under the light switch on the left of the dashboard. This creates additional space in the centre console, as the handbrake lever is no longer required.

When the button is pressed at speeds of over four km/h, the parking brake acts as an emergency brake, activating all four wheel brakes via the ESP^®‘s hydraulic unit.

In conjunction with the 7G-DCT automatic transmission, the parking brake offers a particularly convenient mode of functioning: when the driver accelerates sufficiently after fastening their seat belt, the parking brake is released automatically.

Aerodynamics

Saving fuel the aerodynamic way

With a drag coefficient (Cd) value of 0.27, the aerodynamic experts at Mercedes-Benz succeeded in creating another masterpiece with the A-Class.

And the A 180 BlueEFFICIENCY Edition due to follow later is even able to exceed this record for hatchback vehicles: thanks to a number of aerodynamic enhancements, this beacon of efficiency achieves a Cd value of 0.26.

Countless flow simulation studies on the computer and a great deal of fine tuning in the wind tunnel resulted in a clear goal: to enhance the basic shape of the A-Class design further, with a view to achieving an exceptional drag coefficient.

This is no easy task, particularly for a hatchback model with a short rear overhang. But an improvement in the Cd value of just one hundredth will reduce fuel consumption by one tenth of a litre per 100 km when driving on the motorway at approx. 120 km/h. Based on NEDC figures, this corresponds to a CO₂ reduction of one gram per kilometre.

With a Cd value of 0.27 and a frontal area of 2.20 m², the drag area (CdA) is less than 0.6 m² – a benchmark figure for hatchback vehicles in this segment.

The detailed work behind this development is highlighted by the following examples:

The distinctive side spoilers next to the rear window (“finlets”) help to create a run-on design which significantly reduces the disruptive longitudinal vortices generated at the D-pillars.
Flow losses at the front wheel arches have been reduced substantially with the aid of patented serrated wheel spoilers at front and rear, slots in the wheel arches and optimised hub caps. These measures result in improved wind flow around the wheel arches.
- The A-Class has an adjustable radiator shutter, already familiar in larger model series. The louvres behind the radiator grille are for the most part closed when there is no specific need for cooling air.
The underbody has also been aerodynamically enhanced: the main floor panel features extensive cladding up to the rear wheel arch, followed by additional cladding of the rear axle. The rear silencer has also undergone aerodynamic optimisation.
The new A-Class features exterior mirrors which have been optimised in terms of a number of details and already proven their excellent aerodynamic properties in large model series such as the S, E and C-Class, and also the B-Class. The position of the exterior mirror is adjusted in respect of the A-pillar in such a way that the airflow is directed along the side window without any significant interference or disruption.

The exterior mirrors and the low stepped height of the A-pillars reflect the fact that the work conducted in the wind tunnel was not just about optimising the flow conditions, but also about minimising wind noise.

And in addition to aerodynamics and aeroacoustics, there is often another discipline to consider: in terms of water management too, the flow around the exterior mirrors and the A-pillars also has to be optimised in the wind tunnel in order to guarantee good visibility is maintained towards the rear and at the sides during wet weather.

More than with previous model series, in the case of the A-Class the aerodynamics experts at Mercedes-Benz made particular use of flow simulation (CFD, Computational Fluid Dynamics): each component was first improved over several cycles using flow simulation before having its aerodynamic properties put to the test in the wind tunnel.

Digital flow simulation is based on so-called finite volumes as a mathematical model. A volume net is formed from around 60 million hexahedrons, or cubes, and is based around the CAD data of the new A-Class. This enables the driving cycle to be simulated over a free area in a large virtual wind tunnel. The Mercedes engineers generate the airflow using a predetermined turbulence level.

Setting new standards in terms of Cd value and consumption: BlueEFFICIENCY Edition

Due to follow later is the A 180 CDI BlueEFFICIENCY Edition boasting even better consumption levels. It is among the most efficient vehicles of its class: thanks to a series of additional aerodynamic optimisation measures, it has been possible to reduce its Cd value from 0.27 (standard model) to 0.26.

These measures include:

partially covering the upper part of the radiator grille
aerodynamically shaped spring link coverings to improve the underbody airflow at the rear axle
- lowering of the suspension by 15 mm

Production

At home in the centre of competence for compact cars

The first new A-Class vehicles will be rolling off the production line in Rastatt (Baden, Germany) from the September 2012.

The entire factory has been extended and modernised for this purpose, developing it into a centre of excellence for compact vehicles from Mercedes-Benz at an investment volume of 600 million euros.

In addition, a new factory has been built in Kecskemét, Hungary at a cost of 800 million euros. This is where the B-Class will initially be produced, in addition to Rastatt, to create more capacity for the A-Class at the plant in Baden and allow for more flexibility overall in the production of compact class vehicles.

The company is thus investing a total of around 1.4 billion euros in the two plants. This follows on from Daimler AG’s investment of around 900 million euros in the Rastatt factory for the second-generation A-Class and B-Class between 2002 and 2005.

A new production building has been installed alongside the existing buildings in Rastatt. The new building houses the body shell shop.

The body shell shop has a direct rail link, enabling the direct delivery and unloading of parts at the production shop. The additional body shell shop covers an area of around 66,000 square metres.

Parts from the local region are also to be installed here: after a construction phase of only twelve months, a new press shop opened in nearby Kuppenheim in May 2011 as part of Mercedes-Benz’s Gaggenau plant.

This entailed investments totalling around 70 million euros.

The new press shop is equipped with an interlinked press line, two gripper transfer presses and 24 welding lines with a total of 130 industrial robots for the purposes of component production.

The new building has been provided with a sound-absorbing wall and double sound-absorbing doors on the side facing the local residents.

All presses are additionally fitted with state-of-the-art vibration dampers which prevent the emission of vibrations into the surrounding environment.

The shop also incorporates an air-conditioned measuring centre, where the quality of the pressed parts and welded components undergoes continuous monitoring.

Around 600 different components are produced in Kuppenheim: outer skin components, structural components and welded components for the generations of the A- and B-Class and for Mercedes-Benz trucks.

The press shop currently has a workforce of around 130. If production is running to full capacity in 2015, around 280 people will be employed at the plant. Pressed parts for the A and B-Class are also supplied by the Sindelfingen factory.

Integrated production set-up comprising Rastatt and Kecskemét factories

The completely new factory in Kecskemét, Hungary. was inaugurated in March 2012. It comprises a press shop, body shell shop, paint shop and assembly shop. The two factories form an integrated production set-up under the direction of the Rastatt plant manager.

Rastatt will serve as the headquarters for compact class production, with four model variants of the new compact class to be manufactured in Baden and two in Hungary.

This set-up provides Mercedes-Benz with the necessary flexibility to respond to shifts in demands and to cope with the expected growth in the production volume.

The Rastatt factory had a workforce of around 6100 at the start of 2012, and a further 500 will be employed in the course of the year. When the set-up is running to full capacity, Kecskemét will employ around 3000.

Hungarian employees have been undergoing extensive training in Rastatt for some months now, while experts from Rastatt are on site in Kecskemét to ensure a smooth start-up of operations at the factory.

The two plants are linked by a regular bus service.

The plant in Rastatt commenced production operations in May 1992. Up until 1996 it initially produced the E-Class, and from 1997 it became home to the new A-Class.

More than 2,100,000 vehicles making up the first two generations of the A-Class have been sold.

The six-speed manual transmission

Comfortable manual gearshifts

The new six-speed manual transmission was developed in parallel with 7G-DCT. They share a number of common parts and are both produced in Gaggenau and Rastatt.

The three-shaft transmission is also very compact (length 345 mm) and light (dry weight 46 kg) and incorporates a number of special features for particularly pleasant gearshifting.

An integrated magnet on the gearshift shaft is detected by a Hall sensor. The idle position is identified in this way, making the start/stop function possible. The signal for reverse gear activates the reversing lights.

The large spread of 6.7 allows a reduction in engine speed while at the same time ensuring that sufficient tractive power is available when moving off with a fully laden A-Class and trailer up to a gross weight of 3.4 tonnes.

The clutch is operated hydraulically and the gears are actuated via cables.

The overhead camshaft with third and fourth gears and the reverse gear do not run in the oil bath. This reduces drag torque, thus facilitating gear shifting at low temperatures in particular.

The three-cone synchronisation of the first two gears serves the same purpose, while the following gears are provided with two-cone synchronisation.

The weight-optimised cast aluminium shift forks are installed on anti-friction bearings on the shift rods, in order to reduce the shift forces.

The 7G-DCT dual clutch transmission

Dynamic and efficient

Drawing on over 50 years of experience in the development and production of automatic transmissions, Mercedes-Benz ventured into new technical territory with the 7G-DCT dual clutch transmission: the new system is an automated three-shaft manual transmission consisting of two subtransmissions, each with its own clutch.

Both actuation of the clutches and gear shifting take place fully automatically and without any interruption in tractive power. This allows a particularly comfortable but nevertheless dynamic mode of driving.

Thanks to its seven gears it offers an exceptionally large spread of up to 7.99. This means that a very short transmission ratio is available when moving off on an uphill slope with a high payload, for example, while during cruising the engine speed can be lowered considerably.

The efficiency of this transmission leads to a nine percent improvement in fuel consumption compared to the CVT employed in the A-Class to date, and betters the consumption with a manual transmission.

At a length of 367 millimetres and a weight of 86 kilograms, the 7G-DCT is more compact and lighter than the transmissions in this torque class which have been available on the market to date. The clutches take the form of oil-cooled multi-disc clutches.

The specially developed hydraulic fluid is actively cooled, thus ensuring correct functioning of the transmission even under extreme conditions, despite the comparatively low filling level of six litres.

Excess engine heat can also be transferred to the transmission, which improves its efficiency.

For the first time on this type of unit, the transmission is supplied with oil by two oil pumps – one mechanical and one electric. The electric pump maintains the oil pressure when the engine is switched off via the start/stop function.

This means that the transmission is immediately operational when the engine is restarted and the vehicle can move off again without any delay.

In addition, the electric pump is able to support the mechanical pump when peak loads apply, enabling a more compact and efficient design for the mechanical pump.

Another new feature is electric activation of the hydraulics for the parking lock, which is locked by mechanical means.

This “park by wire” function enables the transmission selector lever to be positioned as desired: it is located in the form of a steering column lever on the right behind the steering wheel in the A-Class.

In combination with the electric parking brake, additional space has thus been created in the centre console for additional stowage facilities.

Three gearshift modes are available to the driver:

ECONOMY: In this mode, the transmission performs gearshifts fully automatically and particularly comfortably. The gears are selected with due regard to a particularly economical style of driving at low revs.
SPORT: The transmission performs gearshifts fully automatically. The shift and response times are shorter, with gearshifts at higher engine speeds.
- MANUAL: In this mode, the driver operates the transmission manually via shift paddles behind the steering wheel. The engine speeds at which the gears are shifted can therefore be freely chosen.

In ECO or Sport mode, the driver is still able to intervene manually in the gear-shifting process via the shift paddles.

The transmission reverts to the selected automatic mode after the paddles have remained inactive for twelve seconds, or after a longer delay when driving downhill or on winding roads.

A key factor contributing to the overall efficiency and dynamism of the A-Class is the closely coordinated operation of the transmissions and engines.

A continuous exchange of data between the control units ensures that the engines run at the ideal operating point at all times. The 7G-DCT transmission is manufactured at Daimler’s Stuttgart-Hedelfingen plant.

Significant reduction in accident figures thanks to driving assistance systems

Based on real-world accident profiles

Avoid accidents and reduce the consequences of accidents – this is the integrated approach adopted by Mercedes-Benz Accident Research under the heading “Real Life Safety”.

Mercedes-Benz is pursuing this strategy systematically with the new, radar-based COLLISION PREVENTION ASSIST system which is standard in all models in the new compact class.

The company hopes that this will have a similarly positive effect on the incidence of accidents and their severity as other innovative safety features from the brand, such as ESP^®, BAS or DISTRONIC.

Unlike other systems in compact-class vehicles already on the market, COLLISION PREVENTION ASSIST is not intended exclusively to minimise minor accident damage in an urban driving context.

Instead, this solution aims to provide protection against typical rear-end collisions in hazardous driving situations at speeds above 30 km/h.

Field tests carried out by Mercedes-Benz in Europe, the US, Japan and South Africa over a total distance of more than 4.5 million kilometres since 2005 confirm that the most critical rear-end collision scenarios arise at speeds above 30 km/h.

The speed profile of the tests conducted by Mercedes-Benz closely follows the real-world accident data from GIDAS (German In-Depth Accident Study), the largest project to record accident data in Germany.

Mercedes-Benz expects that COLLISION PREVENTION ASSIST will have a significantly positive effect on real-world accidents comparable to that seen following the introduction of ESP^® as standard.

Test results reinforce this view: tests involving 110 car drivers in the dynamic simulator saw the accident rate fall from 44 to 11 percent in three typical situations thanks to the combination of collision warning and adaptive braking assistance.

Accident statistics confirm the potential of driving assistance systems

Driving assistance systems make an important contribution to road safety. This is the result of analyses conducted by Mercedes-Benz Accident Research and investigations carried out by the insurance industry as well as independent bodies. A number of success stories can already be reported:

ESP^®: following the introduction of ESP^® as standard by Mercedes-Benz, the number of driver-related accidents involving the brand’s vehicles in Germany fell by 42% (source: evaluation by Mercedes-Benz of the anonymised accident statistics of the Federal Statistical Office). Over 40% of all road traffic fatalities and 20% of those injured on the roads are victims of driver-related accidents.
Brake Assist (BAS): the accident rate for rear-end collisions involving Mercedes passenger cars fell by 8% following the introduction of BAS as standard (source: evaluation by Mercedes-Benz of the anonymised 50% random sample of the 1998-2003 accident statistics of the Federal Statistical Office).
Mercedes-Benz passenger cars equipped with DISTRONIC PLUS are involved in 7% fewer accidents and the material damage they suffer in accidents is 14% lower (source: IIHS Insurance Institute for Highway Safety).
DISTRONIC PLUS and BAS PLUS are capable of reducing the incidence of rear-end collisions by at least 20% and they can reduce the accident severity in 25% of rear-end collisions according to a statistically significant forecast. These figures are based on a study in which the effectiveness of the systems was assessed by retrospectively simulating real-world accident data with known driver behaviours (source: GIDAS German In-Depth Accident Study). Both systems are available for many Mercedes-Benz model series.
The combination of DISTRONIC PLUS, BAS PLUS and PRE-SAFE^® Brake, which is also available for various Mercedes-Benz model series, is accompanied by a significant reduction in frontal collisions. This was shown by an analysis of replacement part orders for the Mercedes-Benz S-Class in the years 2005 to 2008. The analysis identified the difference in order levels for replacement parts for the front section of vehicles with and without DISTRONIC PLUS.

Passive safety

A strong basis and intelligent protection

“One star is all you need” – the Mercedes-Benz safety philosophy also applies to the new A-Class. Its safety equipment, some features of which are traditionally found in much higher vehicle categories, includes belt tensioners and belt force limiters for the rear seats, too, the PRE-SAFE^®anticipatory occupant protection system and the active bonnet for pedestrian protection.

The line-up also includes seven airbags as standard and the Mercedes automatic emergency call system.

The new A-Class has passed the brand’s rigorous programme of crash tests. This includes not only some 30 different impact configurations, which are laid down as requirements for safety ratings and international type approval, but also nine proprietary crash tests, such as the roof-drop test or the pole impact test, developed by the brand itself.

The ability of the new A-Class to satisfy requirements which go far beyond the statutory conditions in some cases is also demonstrated by an internal offset front collision test against a future luxury-segment saloon from Mercedes-Benz: despite the high impact speed and the fact that it is the smaller accident participant, the A-Class offers its occupants an intact passenger compartment and excellent chances of survival.

The bodyshell structure provides the basis for the high standard of passive safety, both in terms of material – the proportion of high-strength and ultra-high-strength sheet steel stands at 67 percent – and with regard to its structural design.

Key features of the front-end structure are the systematic implementation of an available crash length of 435 millimetres, load distribution over several planes, the new bulkhead and floor concept and the subframe as a deformation element.

A total of three longitudinal member planes – consisting of the straight front longitudinal members, a second, upper plane attached to the front end consisting of extruded aluminium box sections and a third plane at the bottom in front of the subframe – allow impact energy to be reduced in a controlled manner.

The subframe provides the torque support for the transverse engine / transmission block and serves to attach the components for the front axle and steering.

It consists of several steel plates, some in ultra-high-strength steel, and a hydroformed tube. In order to optimise its deformation properties, the subframe is connected via two aluminium struts leading forward to the aluminium radiator mount located under the front end.

In the event of a frontal impact, forces can be discharged at an early juncture into the subframe via this third load path, in order to ensure the best possible energy dissipation.

A plastic crash wedge which is fitted at the rear of the front wheel arches helps to ensure that the wheels do not slide under the front doors in the event of a high-impact crash, irrespective of the turning angles.

This means that it will be possible to open the doors, even after a serious accident.

The bulkhead also incorporates a special feature: so-called “skate runners” in front of the two middle longitudinal members discharge forces into the floor.

The continuous floor structure consists of a total of four straight longitudinal members. The tunnel roof reinforcements at front and rear combine with the tunnel to provide a further closed profile supporting the front end.

Controlled deformation: protection in side-on crashes

Rigid side structures and defined deformation management help to safeguard the survival space for occupants in the event of a side impact.

Elements here include the so-called “pole support”, a member fitted diagonally in the rear footwell between centre tunnel and floor side wall which is intended to prevent the floor from being torn open in the event of side impact with a tree.

High-strength steels are used in the upper area of the B-pillar in order to minimise intrusion and to preserve the passenger cell in case of side impact.

The lower area of the B-pillar is softer, in the interests of energy dissipation. The safety experts at Mercedes-Benz have christened the crack management system on the insides of the B-pillar “vampire teeth”.

In a serious side-on crash, the seat belt retractor presses against the inner wall of the B-pillar. To prevent this from leading to a transverse crack which might affect structural integrity, small, tooth-like recesses define the crack direction.

Pedestrian protection: comprehensive measures including Active Bonnet

The protection of those road users who are most at risk has always been a top priority during the development of Mercedes passenger cars.

The new A-Class features numerous protective measures designed to help lessen the risk of injury to pedestrians.

In order to reduce the loads which arise in the event of a pedestrian impact on the bonnet of the vehicle, the deformation space between the bonnet and the components beneath it has been optimised.

This is achieved in part through the appropriate positioning of components such as control units or fluid reservoirs in the engine compartment.

In the case of the A-Class, with its sporty, low-slung body, an active bonnet is also used. In the event of a pedestrian impact, sophisticated sensors combined with intelligent algorithms trigger actuators in the area of the bonnet hinges.

These raise the bonnet by 65 millimetres. The additional space which this creates between the bonnet and the components in the engine compartment means that a head is subject to comparatively low internal acceleration forces on impact.

The deformation characteristics of the bonnet have been developed specifically to meet these requirements. Reductions in the impact loads can be achieved by using aluminium and reinforcing the inside face of the bonnet.

On all seats: intelligent restraint systems

The A-Class protects its passengers with up to nine airbags. The standard complement comprises driver and front-passenger airbag, a kneebag for the driver, large thorax-pelvisbags incorporated in the seat to protect the chest, stomach and pelvis area and windowbags.

The windowbags extend over both rows of seats to the A-pillar triangle. They serve to protect the occupants’ heads from hard contact in the event of side impact and can also help to keep limbs inside the vehicle in an accident.

The driver and front passenger airbags operate in two stages, according to the expected severity of the impact. The gas generator first of all fills the driver’s airbag with 60 and the front passenger’s airbag with 70 per cent gas.

If a more severe impact is forecast, the second stage of the gas generator will additionally be activated after a delay and the airbags will be filled at a higher pressure level. Sidebags for the rear are optionally available.

The high safety expertise of the A-Class’s developers is reflected in a host of details. The deformable steering column yields by up to 100 millimetres when the driver exerts pressure on the airbag as a result of forward displacement in an accident, for example.

The comfort features also reveal a fine touch: the driver’s airbag is connected to a vibration absorber in the steering wheel to reduce vibrations, for example.

The head restraints for driver and front passenger are new developments. The onus in developing the new restraints was on further reducing the risk of whiplash injury.

Key to effective whiplash prevention is the best possible adjustment of the distance from the rear of the occupants’ heads.

The restraint incorporates a button for this purpose on the left-hand side (as seen in the direction of travel). This release mechanism can be pressed to unlock the head restraint and increase the distance between head and head restraint.

The button does not need to be pressed in order to reduce the distance. This enables single-handed operation in all adjustment positions.

Family-friendly: comprehensive precautionary measures in the rear

In developing the new A-Class, the Mercedes-Benz safety experts have also attached great importance to the safety of the rear-seat occupants.

The new model therefore meets the relevant requirements of the Japanese and Chinese NCAP institutes which also take account of factors such as the ease of use of the rear seat belts.

Experts believe that Euro NCAP will extend its rating programme to include rear-seat safety in the medium term.

The A-Class is already prepared for this and is a role model in this respect – both within and beyond its own vehicle category – with features such as standard-fit belt tensioners and belt force limiters for the outer rear seats.

A torsion bar in the roller mechanism twists when the load on it exceeds a defined level. In this way the belt force is limited and with it the load on the seat occupant.

The A-Class’s family-friendly features also include the ISOFIX child seat securing system on the outer seats. Child seats can additionally be fixed to the vehicle by means of special anchorage points with top tethers.

Innovation in the compact class: anticipatory occupant protection system

The PRE-SAFE^® anticipatory occupant protection system is available in the A-Class for the first time. This represents a further step in the on-going democratisation of this innovation, which was premiered in the S-Class in 2002.

PRE-SAFE^® from Mercedes-Benz uses the time between detection of a potential accident situation and a possible collision to initiate preventive protection measures, thus reducing the loads exerted on the occupants in the event of a crash by up to 40 percent.

Core features of PRE-SAFE^® are reversible belt tensioning, the closing of side windows and sliding sunroof when critical lateral dynamics are detected and adjustment of the fully electric front passenger seat with memory function to an ideal position for maximum effectiveness of the restraint systems.

PRE-SA FE^®is activated when one of the following parameters is met: emergency braking, panic braking, pronounced over- or understeering, critical steering movements or heavy support by adaptive Brake Assist.

Mercedes-Benz automatic emergency call system: faster assistance at the scene of an accident

In combination with COMAND Online, the new A-Class is equipped with the Mercedes-Benz emergency call system. As long as COMAND Online is connected to a mobile phone, the Mercedes-Benz emergency call system can automatically alert the emergency services within a matter of minutes in the event of a serious accident.

After the airbags or belt tensioners are triggered, the vehicle’s exact GPS position and vehicle identification number (VIN) are sent by SMS to a special emergency centre, with positional data also being transmitted using the DTMF method (dual-tone multi-frequency) at the same time.

Even if the occupants are unconscious or unsure of exactly where they are because they are on a holiday trip, for example, the emergency services alerted by the emergency centre will be notified quickly with accurate information.

The driver can also make the emergency call manually as “MB emergency call” is always the first entry in the system phone directory.

On receiving the call, the emergency centre establishes voice contact with the vehicle occupants in a matter of seconds.

A particularly practical aspect in an emergency is that the communication is held not in the language of the country where the accident has occurred but in the language which the driver has preset in COMAND Online.

Other than any mobile phone communication charges, which would only arise in the event of an actual emergency call, no charges are incurred by the driver for the emergency call facility and no contractual relationship – other than the regular mobile phone contract – is required.

The driving assistance systems

Radar-based collision warning system as standard

The A-Class provides its drivers with comprehensive support and protection by means of numerous driving assistance systems, from drowsiness detection with ATTENTION ASSIST to proximity control with DISTRONIC PLUS.

These assistance systems, which until now were reserved for higher vehicle segments, are based on state-of-the-art radar, camera and sensor technology and are designed to address the common causes of accidents, such as inadequate distance, fatigue and darkness.

In an innovative move in the compact segment, the A-Class is equipped as standard with a radar-based collision warning system with adaptive Brake Assist, a combination which lowers the risk of rear-end collisions.

The COLLISION PREVENTION ASSIST system gives a visual and audible warning to alert a possibly distracted driver to identified obstacles, and prepares Brake Assist for the most precise braking response possible.

This is initiated as soon as the driver operates the brake pedal decisively.

Unlike other assistance systems in compact-class vehicles already in the market, COLLISION PREVENTION ASSIST is not intended exclusively to minimise minor accident damage in an urban driving context.

Instead, this innovative solution aims to provide protection against typical rear-end collisions in hazardous driving situations at speeds above 30 km/h.

Mercedes-Benz expects that COLLISION PREVENTION ASSIST will have a significantly positive effect on real-world accidents comparable to that seen following the introduction of ESP^® as standard.

The radar-based COLLISION PREVENTION ASSIST system with adaptive Brake Assist

can recognise an inadequate distance from a vehicle ahead in the speed range between 30 and 250 km/h and warn the driver;
can recognise when the gap is decreasing. In case of a detected imminent danger of collision, the driver is provided with a visual and audible warning;
can recognise stationary objects ahead of the vehicle at a speed of up to 70 km/h and issue corresponding warnings;
can adapt the activation threshold for the warning and adaptive Brake Assist to given driving situations, e.g. bumper-to-bumper traffic;
calculates the precise braking force ideally needed to avoid an accident when danger of collision is detected and makes best possible use of any distance remaining. This means that the driver behind also has a better chance of avoiding a rear-end collision.

The brake pressure is adjusted if the situation changes – if the vehicle ahead accelerates, it is decreased to the level the driver requires; if the distance to moving and stopping vehicles decreases, the brake pressure is increased further.

When the vehicle is equipped with PRE-SAFE^®, COLLISION PREVENTION ASSIST provides one of the activation parameters for the anticipatory safety systems, such as the belt tensioners.

Electronic helpers: all the other assistance systems at a glance

Active Parking Assist, which is available as an option for the A-Class, has been developed on the basis of the PARKTRONIC system familiar from other model series.

Ten ultrasonic sensors mounted in the front and rear bumpers measure the length of potential parking spaces at the left and right sides of the road.

Once a suitable space has been identified, the driver stops the vehicle, selects reverse gear and activates the automatic parking assistance system via the controls on the multifunction steering wheel.

The system calculates a suitable manoeuvring pattern with a maximum of five moves to complete the parking operation.

The driver is assisted by the automatic actuation of the electromechanical steering during the parking process but still has to operate the accelerator and brake.

The speed is limited to 10 km/h during the parking process. Parking in spaces situated along slightly curved roads is also supported.

Automatic steering to exit the parking space is a new subfunction. If the vehicle has been parked using Active Parking Assist, the vehicle can be steered out of the parking space in the direction corresponding to the activated direction indicator. Here, too, the driver has to operate the accelerator and brake.

As soon as the vehicle has assumed a sufficient angle to exit the parking space in one straight move, the wheels are set to the straight ahead position, the process ends and the driver assumes steering control again.

The process is completed at the latest when the vehicle is at an angle of 45 degrees relative to the starting position.

The democratisation of safety comprises a series of additional assistance systems:

Adaptive Highbeam Assist: when vehicles are detected ahead of or oncoming to the vehicle, this system automatically dips the beams and adjusts the range of the headlamps appropriate to the distance. The driver benefits from a longer dipped beam range and does not generally need to switch manually between main and dipped beam.
Blind Spot Assist: employs two additional radar sensors at the rear of the vehicle to warn the driver before a lane-change if a vehicle has been detected in the exterior mirror’s blind spot.
Lane Keeping Assist: a camera behind the windscreen recognises clear carriageway markings and can give a warning if the car is about to leave its lane unintentionally.
ATTENTION ASSIST (standard): provides a warning when typical signs of drowsiness are detected. The system’s highly sensitive sensors observe the driver’s behaviour and can recognise – especially on the basis of how the steering wheel is being moved – if the driver is becoming drowsy or inattentive.
Speed Limit Assist: a camera fitted behind the windscreen detects speed limit signs at the roadside and compares this data to information contained in the GPS system or the digital map. The relevant speed limit is then displayed in the instrument cluster.
Brake hold function: when stopping, for example at traffic lights, the driver merely has to press the brake pedal slightly more firmly. They can then take their foot off the brake pedal and the brake will remain engaged until they move off again. The brake is released automatically when the driver steps on the accelerator.
Hill-Start Assist: this function is able to prevent the vehicle from rolling back unintentionally when moving off on an uphill slope.
Reversing camera: integrated in the handle strip on the tailgate, the reversing camera features a wide-angle lens. When reverse gear is engaged, the image from the camera is transmitted to the screen of the Audio 20 system or the COMAND system. Static and dynamic guide lines assist the driver during manoeuvring.
DISTRONIC PLUS: the radar-based adaptive cruise control supports the driver at speeds between zero and 200 km/h by maintaining the distance to the vehicles in front. In doing so it is able to apply the brakes to bring the vehicle to a complete standstill and also accelerate it again. As a result, the system is also particularly convenient in stop-and-go traffic. If the system detects that the distance is being reduced too quickly, it warns the driver with both visual and audible signals.

Cruise control with SPEEDTRONIC: the cruise control maintains the pre-set speed. The additional SPEEDTRONIC function ensures that the stored speed is not exceeded.

Both functions come as standard with the 7G-DCT dual clutch transmission and are optionally available for the models with manual transmission.

Multimedia systems

Always on

Mercedes-Benz has now integrated the iPhone^® comprehensively into the user experience of the new A-Class. Drivers will now have access to all of the key content of their iPhone^®.

This content can be viewed via the in-vehicle display and the device operated via the controller on the centre armrest, all of which is made possible thanks to the Drive Kit Plus for the iPhone^® and an app concept developed by Daimler in-house.

In addition, with COMAND Online drivers can enjoy a fully integrated multimedia system, while with the Audio 5 USB (standard) and the Audio 20 CD there is a choice of two audio systems to suit every budget.

With the seamless integration of the iPhone^® into the vehicle in conjunction with the new revolutionary user interface design, Mercedes-Benz is able to offer the Facebook generation a natural home on four wheels in the new A-Class.

In addition to Facebook, Twitter and so on, the Drive Kit Plus for the iPhone^® (expected to be available as an accessory from the fourth quarter of 2012, and as an optional extra ex-factory from the first quarter of 2013) together with Daimler’s app concept, is able to bring other digital lifestyle services and content into the vehicle.

The highlights include:

Personalised internet radio by AUPEO! Personal Radio, which offers radio stations that compile an individual program for listeners and recommends similar music by genre or artists based on personal taste
Siri voice control system (expected to be available from the first quarter of 2013)
The advanced navigation software from Garmin, with internet-based real-time traffic information, online POI searches and 3D map display, all of which work even in combination with the entry-level multimedia system Audio 20
A socially interactive experience involving “sharing”, “posting” and the integration of music and other content from social networks including text-to-speech
- An intuitive “car finder” which automatically stores the vehicle’s location. Pedestrian navigation makes it completely easy to find your way back to the car

New here is also the contextual and location-based display of menu content under the headings “Social”, “Media” and “Places”. The basic logic behind this was presented by Daimler for the first time in January of this year at the Consumer Electronics Show (CES) in Las Vegas.

Appearing under the heading “Social”, for example, are the various friends and latest news from the social networks.

The user interface design is unique and revolutionary. Transparent symbols are illuminated in red to create three-dimensionally arranged navigation levels.

Within the three-dimensional illustration provided by this menu structure, the user can move intuitively between the various functions in fluid, animated transitions.

The user interface concept was designed and implemented by designers and engineers in the Mercedes-Benz research and development centre in Palo Alto, California/USA.

Enlarging the display of content on the screen to an appropriate format for use in a vehicle and allowing it to be controlled through the ergonomically positioned Controller on the centre armrest makes operating the system both safe and easy.

The iPhone^® is connected through an interface developed by Mercedes-Benz Accessories GmbH. This allows content to be fed directly from the graphics output of the device to the display of the vehicle. At the same time, the iPhone^® is both powered and charged automatically while it is being used.

Full iPhone^® integration is not only possible in conjunction with the COMAND Online multimedia system. All functions, including navigation, can also be used even with the entry-level Audio 20 system.

Overview of other multimedia systems

COMAND Online also offers internet access. Customers can either surf the web as they wish while the car is stationary or call up a Mercedes-Benz app whose particularly fast page loading and simple operation make it suitable for use while driving.

Integrated apps include Google™ Local Search and Weather and the facility for downloading a route which has previously been configured on a PC using Google Maps and transmitted to the car.

In addition, apps for Google™ Streetview and Google™ Panoramio are available for COMAND Online. Streetview enables locations all over the world to be seen in 360-degree perspective views and at street level.

Panoramio allows access to millions of photographs which have been taken and uploaded by other uses at locations all around the globe.

Streetview and Panoramio thus provide comprehensive means of studying routes and checking out sights and destinations before embarking on a journey.

A new feature is the “News” app which enables news on politics, finance and technology to be called up online in the vehicle. Information is displayed in such a way that it is clearly legible while on the move.

Further apps, such as stock market news or a parking space finder, can be also be accessed via the Mercedes online shop (http://apps.mercedes-benz.com).

The high-resolution colour display has a diagonal of 17.8 cm. The basic colour scheme of the central display is silver grey. Photos can be shown on the large screen and turned over manually, as in a slide show.

Where the audio equipment is concerned, too, new types of representation bring a fresh look and more convenient operation.

The new Cover Flow function, for instance, sorts the title images of the music albums stored in a carousel-like form, sothat the A-Class driver can easily leaf through their music collection – even if it is rather on the large side: the memory for compressed audio files (mp3, wma and aac formats) is now 10 GB in size.

Greatest convenience is afforded by the Music Search function, which enables drivers and passengers to search the hard disc, SD memory cards, USB sticks, CDs and DVDs for specific music tracks and artists.

The search can be according to various criteria, for instance album, music category or composer. If a name needs to be entered, the software will also tolerate spelling mistakes.

The driver is therefore able to devote their full attention to the traffic.

As a further advantage, the occupants are able to search all the connected media and devices simultaneously.

The fast hard-disc navigation system of COMAND Online also has added functions. New features include a 3D display with three-dimensional city views.

Also new: routes covered can be recorded and repeated later, specific personal destinations can be imported via an SD card and four alternative routes can be displayed on the navigation map, one of them a particularly economical variation.

Mercedes-Benz customers in Europe receive the current cards for their COMAND Online multimedia system free of charge for three years.

Authorised Mercedes-Benz dealers upload the updates for navigation data in 39 European countries into the navigation system when the customer visits their premises.

In Europe, COMAND Online also comprises Speed Limit Assist, which receives its information for traffic sign recognition via a camera and navigation database.

COMAND Online also includes the LINGUATRONIC voice-operated control system for audio, telephone and navigation.

The new “One Shot” input function for the navigation system is particularly convenient, whereby the place and road can be spoken directly after one another.

This function is currently available in seven languages and significantly enhances ease of operation. With COMAND Online and LINGUATRONIC, music can also be conveniently searched for in the A-Class via voice control.

The system first asks in which category it should conduct the search (artist, title, year).

The category is selected by saying it or by saying the row number of the relevant category which appears on the screen. This is then followed by further questions about title, artist or album.

Fitted as standard is the Audio 5 USB unit. In addition to an AM/FM tuner and an audio amplifier, it features a built-in three-line display. Portable storage media can be connected via the USB and AUX connectors in the centre console.

A pre-installation option for iPhone^® with hands-free function is also available as an optional extra for the Audio 5 system.

If the iPhone^® is connected to the vehicle via a cradle then the radio is muted during telephone calls. The mobile’s battery is charged via the vehicle’s on-board power supply.

The Audio 20 CD system has a twin tuner, mp3-capable CD player and a USB connector in the centre console. The colour display has a diagonal of 14.7 cm.

Thanks to a “cover art” function the title images of the music albums currently being played are shown if their details are stored in the audio file.

A top line in the Audio 20 CD’s menu navigation makes orientation easier and can be operated via the controller. The settings for the air conditioning are also displayed on the telematics screen (when in use), as is the fuel consumption over the past 15 minutes.

The Bluetooth functions have also been extended: the mobile’s phone book can now be automatically transferred en bloc when connected, and wireless music reproduction is possible from Bluetooth-capable terminals. Plus text messages can also be displayed.

As an optional extra the Audio 20 CD can be combined with a 6-disc CD changer, Media Interface, harman/kardon^® sound system, Convenience Telephony in the armrest, digital radio (DAB) and the new Becker^® MAP PILOT entry-level navigation solution.

The Becker^® MAP PILOT makes a low-cost navigation function, which is also suitable for retrofitting, available for the Audio 20 CD radio.

Its advantages over aftermarket solutions include integrated operation via the central controls, voice output via the vehicle’s loudspeakers and display on the Audio 20 screen, a concealed location in the glove compartment and updating and expansion options via an internet portal.

Mercedes-Benz developed the “Logic7” surround sound system together with audio specialists harman/kardon^®. Based on technology never before seen in a car, this high-end system delivers three-dimensional sound as a natural 360-degree musical experience for all passengers.

The audio signals are distributed via a 450-watt multi-channel DSP amplifier connected to twelve high-performance loudspeakers. In conjunction with COMAND Online a multichannel listening experience with Dolby Digital 5.1 and DTS is possible.

The Media Interface is available as an optional extra. The universal interface enables mobile audio devices such as an mp3 player or iPod^® to be connected to the vehicle’s telematics system.

These devices are then operated via the head unit, the central control unit or the steering wheel buttons. By making use of USB 2.0, the new generation of the Media Interface provides quicker display and extended data selection.

Interior design

Extraordinary perceived value

The starting point for the interior design was the interior sculpture “Mercedes-Benz Aesthetics No. 2” presented at the Detroit Motor Show in 2011 and which directed attention to the new Mercedes-Benz design language in the vehicle interior, too.

The first concrete implementation of this was shown in April 2011 with the “Concept A-CLASS”.

“The inspiration from aircraft design is continued in the A-Class”, explains designer Jan Kaul. “The instrument panel is clearly divided into an upper part inspired on a wing profile and a muscular lower section.

This creates the impression that the upper section is supported by a muscle.”

The process used for the production of this muscle allows diverse soft surface textures. It is thus possible to create different surface appearances with an attractive play of lights thanks to three-dimensional structures embedded in foil.

“The interior of the A-Class represents a big step forward in terms of quality – both in the materials used and in the consistency of the design” says Kaul.

Both objectives have been achieved with the help of a specific design idiom and through the various combination options possible with the high-quality materials selected.

All trim elements have been given an electroplated finish, resulting in real metal surfaces with “cool touch” effect. The work has been executed with considerable care and attention to detail, so that they appear to have been moulded in one piece.

The instrument panel incorporates five round vents. “Like brilliant jewels they underscore the superior quality of the vehicle interior”, explains Kaul.

The outer rings of the round vents have a high-quality electroplated finish. The airflow direction is governed by an insert that is reminiscent of an aircraft turbine and reveals a meticulous attention to detail.

This too has an electroplated finish in silver-chrome. The free-standing display screen features a black piano-lacquer-look front panel and a flush-fitting silver frame.

The instrument cluster comprises two large round instruments, each with a small dial set within it. When at rest, the dial needles stand at 6 o’clock.

The pointer inlays are in white, although with the sportier design and equipment lines such as Urban and AMG Sport they are in red.

The dials on the sporty equipment lines and packages are coloured silver with a chequered flag effect. The 3-spoke steering wheel comes with 12 function buttons and an electroplated bezel.

The centre dome and console, as well as the positioning of the various elements such as the head unit, lower control panel, air conditioning operating unit, stowage compartments, rotary pushbutton and armrest, reflect the findings of the ergonomics experts at Mercedes-Benz.

An extensive range of seat coverings, in terms of material (e.g. leather, fabric, ARTICO/fabric), colour combination and also geometry, provides scope for a broad range of individualisation options.

Sports seats with integrated head restraints are available with all optional design and equipment lines.

The sporty nature of the seats is emphasised by the opening between the upper edge of the seat backrest and the head restraint.

On the back of the front seats this opening is edged with a frame in silver chrome and, in conjunction with the Light and Sight package, can also feature ambient lighting.

Designer Jan Kaul sums up: “If you were to take a seat in the A-Class with your eyes closed – you would never think, upon opening your eyes, that you were sitting in a compact-class vehicle.”