The Mercedes-Benz SL 600 V12, produced between June 1993 and August 1995, represents the pinnacle of performance and luxury within the R129 generation of the SL roadster. This variant, powered by a massive 6.0-liter V12 engine paired exclusively with an automatic transmission, was positioned as the flagship model, offering a significantly more potent and refined experience than the SL 320, SL 280, or even the later SL 500 models. The R129 SL, launched in 1989, aimed to revive the iconic SL lineage with modern technology and a focus on comfort and safety, and the 600 V12 embodied these aspirations at their most extravagant.
Powertrain & Engine Architecture
The heart of the SL 600 V12 is the M120.981 engine, a 5,987 cc (365.35 cubic inches) naturally aspirated V12. This engine is a testament to Mercedes-Benz’s engineering prowess, featuring a 60-degree V-angle, a cast iron block, and aluminum cylinder heads. It boasts a relatively conservative 10:1 compression ratio and utilizes multi-port fuel injection. The valvetrain employs dual overhead camshafts (DOHC) with four valves per cylinder, contributing to its impressive power output. The engine produces 394 horsepower at 5,200 rpm and a substantial 570 Nm (420.41 lb-ft) of torque at 3800 rpm.
The engine’s lubrication system requires 10 liters (10.57 US quarts) of oil meeting Mercedes-Benz specifications, and the cooling system holds 19 liters (20.08 US quarts) of coolant. The M120 engine is known for its smoothness and durability, although its complexity does necessitate careful maintenance.
The SL 600 V12 was exclusively equipped with a 4-speed automatic transmission. This transmission, while not as sophisticated as some contemporary units, was robust and well-suited to handling the engine’s considerable torque. The gear ratios were optimized for both comfortable cruising and responsive acceleration. While not offering the driver engagement of a manual transmission, the automatic provided a seamless and luxurious driving experience, befitting the car’s grand touring character.
Engine Code Specifics (M120.981)
The M120.981 engine code designates this specific iteration of the M120 V12. Early versions of the M120 (like those found in the 600SE/SEL) had some issues with head bolt failures, but these were largely addressed in the R129 SL’s version. However, regular inspection and maintenance of the valve cover gaskets and oil lines are crucial to prevent leaks, a common issue with this engine as it ages.
Driving Characteristics
The SL 600 V12 delivers a driving experience markedly different from its six-cylinder siblings. The sheer power of the V12 engine provides effortless acceleration, with a 0-60 mph time of approximately 5.8 seconds and a electronically limited top speed of 250 km/h (155.34 mph). The torque curve is broad and flat, meaning strong pulling power is available across a wide range of engine speeds. This makes overtaking maneuvers and highway cruising particularly relaxed.
Compared to the SL 500, the V12 offers a noticeable increase in performance, particularly in the mid-range. While the SL 500 provided ample power for most drivers, the 600 V12 catered to those seeking the ultimate in performance and refinement. The automatic transmission, while smooth, doesn’t offer the same level of control as a manual gearbox, but it complements the car’s grand touring nature. The weight distribution, however, is slightly front-heavy due to the large engine, which can be felt during spirited cornering.
Equipment & Trim Levels
As the range-topping model, the SL 600 V12 came standard with a comprehensive list of features. Leather upholstery was standard, along with burl walnut wood trim throughout the interior. Power-adjustable seats with memory function, automatic climate control, and a premium sound system were also included. Exterior features included alloy wheels, a color-matched hardtop, and a power-operated soft top.
Optional extras included heated seats, a CD changer, and upgraded leather options. The SL 600 V12 was often specified with a more extensive list of options than lower-trim models, reflecting its status as a luxury flagship. The interior dashboard configuration was largely consistent across the R129 range, but the 600 V12 often featured more exclusive trim materials and detailing.
Chassis & Braking
The R129 SL chassis was designed for both comfort and handling. The SL 600 V12 utilized a coil spring and hydro-pneumatic element front suspension with wishbones and a transverse stabilizer. The rear suspension employed an independent multi-link setup with hydro-pneumatic elements, a transverse stabilizer, and coil springs. This suspension configuration provided a comfortable ride while maintaining good body control.
Braking duties were handled by ventilated discs on all four wheels, assisted by an Anti-lock Braking System (ABS). The braking system was effective, but the increased weight of the V12 engine required slightly more stopping distance compared to lighter SL models. The steering system was a cone worm with recirculation balls and hydraulic power assistance, providing a relatively heavy but precise steering feel.
Market Reception & Comparison
The SL 600 V12 was generally well-received by automotive critics, who praised its powerful engine, luxurious interior, and comfortable ride. However, its high price tag and significant fuel consumption (13.2 l/100 km combined – 17.8 US mpg) limited its appeal to a relatively small segment of the market. Compared to the SL 500, the 600 V12 offered a substantial performance upgrade, but at a considerable cost. Fuel economy was significantly worse, and maintenance costs were higher due to the complexity of the V12 engine. Reliability was generally good, but preventative maintenance was crucial to avoid costly repairs.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | SL |
| Generation | SL (R129) |
| Type | SL 600 V12 (394 Hp) Automatic |
| Start of production | June, 1993 |
| End of production | August, 1995 |
| Engine Model/Code | M 120.981 |
| Engine displacement | 5987 cm3 (365.35 cu. in.) |
| Number of cylinders | 12 |
| Engine configuration | V-engine |
| Power | 394 Hp @ 5200 rpm |
| Torque | 570 Nm @ 3800 rpm (420.41 lb.-ft. @ 3800 rpm) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6.1 sec |
| Acceleration 0 – 60 mph | 5.8 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Fuel consumption (urban) | 20.2 l/100 km (11.6 US mpg) |
| Fuel consumption (extra urban) | 11.3 l/100 km (20.8 US mpg) |
| Fuel consumption (combined) | 13.2 l/100 km (17.8 US mpg) |
| Kerb Weight | 1980 kg (4365.15 lbs.) |
| Max. weight | 2320 kg (5114.72 lbs.) |
| Trunk (boot) space | 265 l (9.36 cu. ft.) |
| Fuel tank capacity | 80 l (21.13 US gal) |
| Length | 4470 mm (175.98 in.) |
| Width | 1812 mm (71.34 in.) |
| Height | 1296 mm (51.02 in.) |
| Wheelbase | 2515 mm (99.02 in.) |
| Transmission | 4 gears, automatic transmission |
Legacy
Today, the Mercedes-Benz SL 600 V12 is a sought-after classic, particularly among collectors and enthusiasts. While maintenance can be expensive due to the complexity of the V12 engine, the car’s unique combination of performance, luxury, and exclusivity ensures its continued desirability. The M120 engine, when properly maintained, is known for its longevity. However, potential buyers should be aware of the potential for oil leaks and the need for regular servicing. The SL 600 V12 represents a high point in Mercedes-Benz engineering and a testament to the enduring appeal of the SL roadster.
