1. A new era of power and prestige: The V12 Mercedes R129

2. Whispered rumours become reality

3. The heart of a supercar

4. Driving dynamics with grace

5. Understated elegance on the outside

6. Luxury within

7. Conclusion

A new era of power and prestige: The V12 Mercedes R129

By the early 1990s, the Mercedes SL had already carved a reputation for itself as a refined, high-performance roadster. But for those who demanded even more from their luxury sports car, Mercedes was quietly preparing something truly extraordinary. The result? The long-awaited arrival of the six-litre V12-powered R129 – a flagship that would redefine what top-tier automotive engineering looked and felt like.

Whispered rumours become reality

For years, enthusiasts speculated about the mythical V12 SL. The idea was floated long before the official launch of the R129 in 1989, with enthusiast magazines teasing a super-luxurious version of the new roadster almost as soon as its design sketches hit the drawing board. By the time Mercedes unveiled the W140 S-Class in 1991 at the Geneva Motor Show – complete with its brand-new M120 V12 – the writing was on the wall. The SL would be next.

It wasn’t just fantasy: early prototypes of the 600SL were already being tested as early as 1989, using converted 500SL chassis. The first pilot builds rolled off the line in August 1991, and full production began in earnest in July 1992. Finally, in October of that year, the 600SL officially launched – and it didn’t disappoint.

The heart of a supercar

At the core of the 600SL was the formidable M120 engine, designated 120.981 in SL form. This all-aluminium 60° V12 had a displacement of 5987cc, with a bore and stroke of 89.0mm and 80.2mm respectively. Featuring twin overhead camshafts per bank, four valves per cylinder, and variable valve timing on the intake cams (adjustable up to 25°), it was a technical masterpiece.

Initially delivering 408bhp and 428lb-ft of torque, the SL’s version of the V12 was slightly reworked. By launch, the power stood at 394bhp at 5200rpm and 420lb-ft at 3800rpm. That minor decrease didn’t affect performance significantly – the 600SL could sprint from 0–100 km/h in just 6.1 seconds (or 5.9 seconds in U.S. spec) and was electronically limited to a top speed of 250 km/h (156 mph).

Fuel economy was, naturally, secondary for most buyers, but Mercedes still managed a respectable 11.3 litres per 100 km (25.0 mpg Imperial, 20.8 mpg U.S.) at a steady 90 km/h. A noteworthy achievement for a 1980kg roadster with a massive twelve-cylinder heart.

Driving dynamics with grace

To handle the additional weight and power, Mercedes upgraded the suspension system with stiffer springs and dampers. Advanced systems like Automatic Skid Control (ASR) and Adaptive Damping System (ADS) were standard, making the 600SL not only quick but composed.

The braking system was also enhanced. Ventilated discs measuring 320mm up front and 300mm at the rear provided powerful, fade-resistant stopping performance. The ABS system was specially calibrated to adapt based on whether the car was cornering or driving straight – a subtle but important refinement.

Understated elegance on the outside

Visually, the 600SL didn’t shout about its status. Only discreet ‘V12’ badges on the front wings and a slightly deeper front bumper on U.S. models gave the game away. The signature tail badge – “600SL” – was short-lived, eventually replaced by the SL600 naming convention in line with Mercedes’ evolving nomenclature.

Optional alloy wheels (SA code 652), a colour-coded hardtop, and the signature SL silhouette made it a head-turner – though more for its elegance than for ostentation.

Luxury within

Inside, the 600SL was every bit the flagship. At a launch price of €111,300, it came fully loaded with nearly every conceivable luxury feature of the era: dual airbags, automatic climate control (CFC-free), cruise control, power seats with memory, seat heating, leather upholstery throughout, and a premium Mexico 2000 stereo system.

To distinguish it from lesser SLs similarly equipped, the 600SL featured unique interior details: a special walnut/leather gear lever, extra wood trim on the centre console, and leather-finished armrests, door pulls, sun visors, and the rollover bar. Rear seats were optional, adding another €1,200 to the build.

Conclusion

The 600SL marked a high point not just for the R129 generation, but for Mercedes itself. It combined the luxury and elegance expected from the brand with cutting-edge engineering and a truly commanding drivetrain. Quietly powerful, lavishly equipped, and built with an obsessive attention to detail, the V12 SL remains a landmark in the marque’s history.

For collectors and enthusiasts today, it’s more than a car – it’s a statement. A rolling tribute to a time when Mercedes dared to put a V12 in a roadster and make it feel as effortless as a stroll down the Autobahn.

Are you already a proud owner of a Mercedes R129? If so, check out our selection of parts for this car at the following link:

https://octoclassic.com/product-category/mercedes-benz/r129

Photos sources: theslshop.com