Stuttgart/Colorado Springs. Mercedes-Benz has set a new record for the diesels in the legendary Pikes Peak hill-climb race with a near-production C 300 d 4MATIC: Test driver Uwe Nittel completed the 19.99 km long route which includes more than150 bends at a range in altitude of nearly 1400 metres in just 11.37 minutes.
“With extensive simulation measures, gruelling durability road tests and exhaustive trial driving at test sites all over the world, Mercedes-Benz’s testing programme is undoubtedly one of the most rigorous in the automotive branch,” says
Prof. Dr Thomas Weber, member of the board of management of Daimler AG, responsible for Group Research and Mercedes-Benz Cars Development.
“Pikes Peak raised the crossbar still further. And the virtually series-production C 300 d 4MATIC demonstrated in this test that sporty performance and clean exhaust technology go together perfectly.”
The test drive at Pikes Peak also demonstrated how well Mercedes-Benz diesel powertrains are adapted to the special requirements of the US market, which include extreme climatic conditions.
The course’s numerous switchbacks put the suspension and the 4MATIC powertrain through their paces when accelerating out of the bends.
Another challenge for the diesel engine was the thin mountain air – the finishing point is an impressive 4301 metres above sea level.
Test driver Uwe Nittel, 46, reports: “Shoving a series diesel saloon with automatic transmission up Pikes Peak sounds like a crazy idea, put it was a lot of fun. And it showed that all the prejudices regarding diesel vehicles are well out of time.”
Nittel comes from rallying: numerous victories in national championships and the rally world championship culminated in the vice world champion’s title in group N (1996). In 2011 he belonged to the team that won the FIA truck racing European championship.
The 150 kW (204 hp) C 300 d 4MATIC (in Europe known as 250 d) fitted with a 7G-TRONIC PLUS automatic transmission competed in the hill-climb race in largely series-production configuration.
As is customary for a racing car, the interior was cleared out. The modifications included the safety measures required by the regulations, such as a roll-over cage, racing tank, fire extinguishing system, enhanced brakes and ultra-high-performance tyres (UHP).
The environment-friendly engine technology remained completely unchanged. Thanks to the highly effective emission control system, the C 300 d is the first diesel model to undercut the American ULEV 70 emissions limits, which are among the strictest in the world.
The engine technology: clean and economical
The C 300 d is powered by a four-cylinder diesel engine with fourth-generation common rail direct injection featuring piezo injectors, two-stage turbocharging and exhaust gas recirculation.
A highly sensitive engine control system responds precisely to the most diverse operating conditions, thereby optimising the combustion processes.
The emission control system incorporates a close-coupled electrically heated oxidation catalytic converter and a diesel particulate filter which is located in the area of the bulkhead. This shortens the regeneration times.
The core of the emission control system takes the form of an SCR (Selective Catalytic Reduction) catalytic converter, with an “AdBlue®” injector connected upstream. “AdBlue®” is a synthetic aqueous urea solution which causes the nitrogen oxides (NOx) to be reduced to harmless nitrogen in the SCR catalytic converters.
Monitoring and diagnosis of the complex exhaust gas aftertreatment processes are performed by various sensors, including a differential pressure sensor, a lambda sensor, NOx and temperature sensors.
The hill-climb race: legendary and gruelling
156 bends and a difference in altitude of 1439 metres over a distance of just under 20 kilometres – the “Broadmoor Pikes Peak International Hill Climb” (PPIHC) in the US state of Colorado is arguably the most spectacular and demanding hill-climb race in the world.
The uphill gradient averages seven percent. The epithet “Race to the clouds” derives from the alpine topography: The race begins at an ample altitude of 2862 metres, and the finishing point at the summit of Pikes Peak in the Rocky Mountains is no less than 4301 metres above sea level. The entire route has been asphalted since 2011.
PPIHC is one of the very oldest motorsport events:Races for automobiles and motorcycles have been held here since 1916, and this year’s event was the 93rd in the course’s history.
The best-known winners include the American Bobby Unser, who won the hill-climb race 13 times in all, Indycar drivers Mario Andretti (1969) and Rick Mears (1976) and rally drivers Michèle Mouton (1984, 1985), Walter Röhrl (1987), Ari Vatanen (1988) and Sebastien Loeb (2013).