The Mercedes-Benz SL (R129) underwent a significant facelift in 1998, continuing production through 2001. Among the various iterations offered, the AMG SL 55 V8 Automatic, produced from May 1999 to July 2001, represented a high-performance variant of the iconic roadster. Positioned as a premium offering within the R129 lineup, it bridged the gap between the standard SL models and the even more exclusive SL 600. This model combined a powerful, naturally aspirated V8 engine with a five-speed automatic transmission, delivering a blend of luxury and exhilarating performance. The R129 platform itself was a successor to the long-running R107, introducing a host of improvements in safety, technology, and overall refinement.
AMG SL 55 V8: Powertrain & Engine Architecture
The heart of the AMG SL 55 was the M113 E 55 engine, a 5.4-liter (5439 cc / 331.91 cu. in.) naturally aspirated V8. This engine, designated with the code M 113.985, produced 354 horsepower at 5500 rpm and 530 Nm (390.91 lb-ft) of torque at 3000 rpm. The engine featured a cast iron block with aluminum cylinder heads, a configuration chosen for its durability and ability to withstand the stresses of high performance. It employed multi-port fuel injection and a single overhead camshaft (SOHC) valvetrain with three valves per cylinder. The compression ratio was set at 10.5:1. Engine oil capacity was 7.8 liters (8.24 US qt / 6.86 UK qt).
The engine was mated to a five-speed automatic transmission, specifically designed to handle the substantial power output. This transmission featured electronic control and adaptive shifting, aiming to provide smooth and responsive gear changes. While not offering the direct control of a manual gearbox, the automatic transmission was well-suited to the SL’s grand touring character. The drivetrain configuration was rear-wheel drive, with power delivered to the rear wheels via a robust driveshaft and differential.
Engine Specifications
Key engine specifications included a 97 mm bore and a 92 mm stroke. The engine’s power-to-liter ratio was an impressive 65.1 hp/liter. The M113 engine was known for its robust construction and relatively straightforward maintenance compared to some of its more complex contemporaries.
Driving Characteristics
The AMG SL 55 Automatic delivered a distinctly different driving experience compared to the lower-powered SL variants. Acceleration from 0 to 100 km/h (0-62 mph) was achieved in 5.9 seconds, while 0-60 mph was calculated at 5.6 seconds. Top speed was electronically limited to 250 km/h (155.34 mph). The automatic transmission, while smooth, did introduce a slight degree of torque converter slip, which could slightly diminish the feeling of direct connection to the engine. However, the ample torque available at lower revs meant that the car felt responsive in everyday driving situations. Compared to a manual transmission equipped SL, the automatic version offered greater ease of use, particularly in urban environments, but sacrificed some driver engagement.
The weight-to-power ratio of 5.1 kg/hp and weight-to-torque ratio of 3.4 kg/Nm contributed to the car’s brisk performance. The engine’s power delivery was linear and predictable, making it easy to modulate throttle inputs. The overall driving experience was one of refined power and comfortable cruising, befitting a luxury roadster.
Equipment & Trim Levels
The AMG SL 55 Automatic came standard with a comprehensive list of features, reflecting its premium positioning. Interior appointments included leather upholstery, wood trim, and power-adjustable seats. Standard equipment also included automatic climate control, a premium sound system, and power windows and locks. The exterior featured AMG-specific body styling, including unique front and rear bumpers, side skirts, and wheels. Optional extras included features such as a panoramic sunroof, upgraded sound systems, and various interior trim options. The R129 facelift brought improvements to the interior design, with a more modern dashboard layout and updated switchgear.
Chassis & Braking
The R129 SL featured a robust chassis designed for both comfort and handling. The front suspension utilized coil springs, wishbones, and a transverse stabilizer bar. The rear suspension employed an independent multi-link setup, also with coil springs and a transverse stabilizer bar. This suspension configuration provided a good balance between ride comfort and handling precision. The car was equipped with ventilated disc brakes on all four wheels, providing ample stopping power. An Anti-lock Braking System (ABS) was standard. The steering system was a cone worm with recirculation balls and hydraulic power assistance.
Tire sizes were 245/40 ZR 18 at the front and 275/35 ZR 18 at the rear, mounted on 8.5 J x 18 H2 and 9.5 J x 18 H2 wheels respectively. The curb weight of the vehicle was 1815 kg (4001.39 lbs), with a maximum weight of 2210 kg (4872.22 lbs) and a maximum load capacity of 395 kg (870.83 lbs).
Market Reception & Comparison
The AMG SL 55 Automatic was generally well-received by automotive critics. It was praised for its powerful engine, comfortable ride, and luxurious interior. However, some reviewers noted that the automatic transmission, while smooth, lacked the engagement of a manual gearbox. Compared to the SL 320 and SL 280 models, the SL 55 offered significantly more performance. Fuel economy, however, was considerably lower, with combined fuel consumption of 12.8 l/100 km (18.4 US mpg / 22.1 UK mpg) and CO2 emissions of 370 g/km. Compared to the SL 600, which featured a V12 engine, the SL 55 offered a more accessible price point and a slightly more focused driving experience.
Technical Specifications
| Body type | Roadster, 2 Doors, 2 Seats |
| Fuel economy (combined) | 12.8 l/100 km (18.4 US mpg, 22.1 UK mpg, 7.8 km/l) |
| CO2 emissions | 370 g/km |
| Maximum speed | 250 km/h (155.34 mph) |
| Acceleration 0-100 km/h | 5.9 sec |
| Acceleration 0-60 mph | 5.6 sec |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 113 E 55/M 113.985 |
| Engine displacement | 5439 cm3 (331.91 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 97 mm (3.82 in.) |
| Piston Stroke | 92 mm (3.62 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 3 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | SOHC |
| Engine oil capacity | 7.8 l (8.24 US qt | 6.86 UK qt) |
| Kerb Weight | 1815 kg (4001.39 lbs.) |
| Max. weight | 2210 kg (4872.22 lbs.) |
| Max load | 395 kg (870.83 lbs.) |
| Trunk (boot) space – minimum | 265 l (9.36 cu. ft.) |
| Fuel tank capacity | 80 l (21.13 US gal | 17.6 UK gal) |
| Length | 4499 mm (177.13 in.) |
| Width | 1812 mm (71.34 in.) |
| Height | 1300 mm (51.18 in.) |
| Wheelbase | 2515 mm (99.02 in.) |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 5 gears, automatic transmission |
Legacy
The M113 engine, found in the AMG SL 55, is generally considered a reliable powerplant, provided it receives regular maintenance. Common issues include occasional oil leaks and potential problems with the electronic throttle body. The five-speed automatic transmission is also relatively robust, although it may require servicing as it ages. Today, the AMG SL 55 Automatic represents a desirable entry point into the world of Mercedes-Benz AMG ownership. Its combination of performance, luxury, and relative affordability makes it a popular choice among enthusiasts. Well-maintained examples continue to command respectable prices in the used car market, and the R129 SL remains a highly regarded classic roadster.
