- Odometer switched from mechanical to electronic
- Option for portable cell phone with voice activated dialing
- Clear front turn signal indicators for US SPEC models
- Bose stereo now standard, rear speakers and subwoofer
- Front fender vents updated; only 2 rounded slots, rather than 3 squared slots
- Bumpers are now body color
- V8 and V12 upgraded to 5 speed electronic transmission; previous transmission was hydraulic 4-speed
- Xenon HID headlamps standard on SL600, optional on SL500
- Addition of side airbags
- A new front-seat occupant-detection sensor could deactivate the right-side airbag when it determined that the passenger seat held less than 26 pounds
- “Sport” package became an option
- Automatic rain-sensing windshield wipers standard
- Three-way programmable garage door opener “HomeLink” transmitters built into the rear-view mirror
- Replaced the earlier climate control panel with one with a much larger LCD
- Remote control uses dual infrared (IR) and radio (RF) control
- V8 engine switch from M119 to M113
- Soft Nappa leather seats replace the perforated leather seats
- Body color door handles
- Tail lights with curved faces replacing the classic square stepped lights
- 17-inch wheels standard: Wheels are now 8.25 x 17″ with 245/45ZR17 tires. Sport package is 8″ (front) or 9″ (rear) x 18″ with 245/40 (f) and 275/35 (r) tires.
- Fiber-Optic digital audio links to the CD player instead of analog copper
- One-touch starter- just turn key, it starts
- Instrument cluster now has silver rings around each gauge
- Oil pressure gauge replaced with oil temperature
- Different engine vanity cover
- Removed the automatic lock on the left rear storage compartment which houses the Bose subwoofer
1999 Mercedes-Benz R129 SL500
1999 Mercedes-Benz SL600
Initially, there were three different engines available, 300 SL with a M103 3.0 L 12-valve SOHC L6 (190 PS (140 kW; 190 hp) at 5700 rpm), 300 SL-24 with a M104 3.0 L 24-valve DOHC L6 (231 PS (170 kW; 228 hp) at 6300 rpm), 500 SL with a M119 5.0 L 32-valve DOHC V8 (326 PS (240 kW; 322 hp) at 5500 rpm), and joined in July, 1992 by the 600 SL with a M120 6.0 L 48-valve DOHC V12 (389 hp/290 kW) @ 5200 rpm).
There was a choice of 5-speed manual or 4-speed automatic for the six-cylinder cars; the V8 and V12 could only be ordered with an automatic gearbox.
In Autumn 1993 Mercedes-Benz rearranged names and models. Also, the 300 SL was replaced by:
SL 280 with a M104 2.8 L 24-valve DOHC L6 (197 hp(145 kW) at 5500 rpm)
SL 320 with a M104 3.2 L 24-valve DOHC L6 (220 hp (161 kW) at 5500 rpm)
Only the 280 was available with a manual gearbox. SL 500 and 600 continued with their respective engines. A second facelift, introduced in late 1998, comprised new external mirrors, 17″ wheels and new bumpers. Also new were the engines,
SL 280 with a M112 2.8 L 18-valve SOHC V6 (204 PS (150 kW; 201 hp) at 5700 rpm), SL 320 with a M112 3.2 L 18-valve SOHC V6 (224 PS (165 kW; 221 hp) at 5600 rpm) and SL 500 ((306 PS (225 kW; 302 hp) at 5600 rpm) — full throttle enrichment removed.
The V12 engine remained unchanged.
In April 1998 at the Turin Motor Show, an updated SL range was presented featuring newly developed engines and a subtly revised design.
The most significant refinements included the introduction of a new generation of V-type engines with 6 and 8 cylinders to replace the 6-cylinder in-line engine featured in the M 104 series and the M 119 series V8-unit.
Thanks to the advent of 3-valve technology and dual ignition, the new engines consume up to ten percent less fuel than their predecessor models and are particularly remarkable for their very low exhaust emissions.
Output levels range from 150 kW (204 hp) in the SL 280 and165 kW (224 hp) in the SL 320 to 225 kW (306 hp) in the SL 500.
The top-of-the-range SL 600 continues to be powered by the M 120 12-cylinder engine producing 290 kW (394 hp).
The SL 60 AMG was discontinued as part of the model improvement program and has not been available since June1998.
The design of the SL has not been radically modified. The aim of the subtle touching-up was to give the sports car an even more dynamic appearance.
Smooth curves govern the new exterior mirrors which have been designed along the lines of the SLK and which represent the most distinctive external feature of the refined models.
Color-coded door handles and bodywork attachments of the new SL models are given a rich finish to match the bodywork.
The size and design of the wheels have also been modified. Indeed, the refined SL models are fitted with new-style 245/45 ZR 17 5-hole light-alloy wheels as standard.