The Mercedes-Benz SL (R230) facelift, produced from 2006 to 2008, represented a significant evolution of the fifth-generation SL roadster. Among the various engine options available, the AMG SL 55 V8 Automatic stood out as a high-performance variant, positioned as the flagship model before the introduction of even more potent AMG versions. This model combined a naturally aspirated 5.4-liter V8 engine with a five-speed automatic transmission, delivering substantial power and luxury in a two-seat convertible package. It was built on the 1HX0 chassis, shared with other Mercedes-Benz models of the era.
AMG SL 55 V8: Powertrain & Engine Architecture
The heart of the AMG SL 55 is the M113.992 engine, a 5.4-liter (5439 cc) naturally aspirated V8. This engine is characterized by its robust construction and high output. It features a short-stroke design (97 mm bore x 92 mm stroke) and a compression ratio of 9:1. The engine utilizes multi-port fuel injection and a Lysholm-type supercharger with an intercooler, contributing to its impressive power delivery. The valvetrain employs a single overhead camshaft (SOHC) design per cylinder bank, optimized for both performance and reliability.
The five-speed automatic transmission (722.6) was specifically tuned by AMG to handle the engine’s substantial torque. This transmission featured adaptive shift programming, adjusting shift points based on driving style and conditions. While not as technologically advanced as some later automatic transmissions, the 722.6 was known for its durability and smooth operation. The drivetrain is rear-wheel drive, providing a classic sports car driving experience. Engine oil capacity is 8.5 liters (8.98 US qt / 7.48 UK qt) and coolant capacity is 13 liters (13.74 US qt / 11.44 UK qt).
Performance Specifications
The M113.992 engine produces 517 horsepower (hp) at 6100 rpm and 720 Newton-meters (531.04 lb-ft) of torque between 2600 and 4000 rpm. This output translates to impressive acceleration figures: 0 to 100 km/h (0-62 mph) in 4.5 seconds, 0 to 60 mph in 4.3 seconds, and 0 to 200 km/h in 14 seconds. The top speed is electronically limited to 250 km/h (155.34 mph). The power-to-weight ratio is 3.6 kg/hp, and the torque-to-weight ratio is 2.6 kg/Nm.
Driving Characteristics
The AMG SL 55 Automatic delivers a distinctly powerful and refined driving experience. The supercharged V8 provides immediate throttle response and a broad torque curve, making it effortless to accelerate in any gear. The five-speed automatic transmission, while not offering the lightning-fast shifts of modern dual-clutch transmissions, provides smooth and predictable gear changes. Compared to the base SL models with smaller engines, the SL 55 offers a significantly more exhilarating experience. It also differs from later SL 63 AMG models, which featured larger displacement engines and more advanced transmissions, offering a different character – the SL 55 is often described as more manageable and less overtly aggressive.
The car’s weight (1885 kg / 4155.71 lbs) is noticeable, but the powerful engine mitigates this, providing strong acceleration and confident passing power. The suspension is tuned for a balance between comfort and handling, offering a relatively compliant ride for a high-performance roadster.
Equipment & Trim Levels
The AMG SL 55 Automatic came standard with a comprehensive list of features, reflecting its position as the top-of-the-line SL variant. Standard equipment included leather upholstery, heated seats with memory function, automatic climate control, a premium sound system, and bi-xenon headlights. The interior featured AMG-specific styling cues, including unique instrument cluster graphics and AMG badging.
Optional extras included features such as a panoramic sunroof, upgraded leather packages, a navigation system, and various driver assistance systems. The exterior could be customized with different wheel designs, paint colors, and trim options. The interior trim could be specified with wood or carbon fiber accents.
Chassis & Braking
The R230 SL chassis features an independent multi-link suspension at both the front and rear, utilizing hydraulic elements. This suspension design provides a comfortable ride while maintaining good handling characteristics. The front suspension incorporates stabilizer bars to reduce body roll during cornering. The braking system consists of ventilated discs at all four wheels, with larger discs (360 mm front, 330 mm rear) fitted to the AMG SL 55 compared to the base models. The car is equipped with ABS (Anti-lock Braking System) as standard. The steering system is a hydraulic power-assisted rack and pinion system, providing precise and responsive steering feel.
Market Reception & Comparison
The AMG SL 55 was generally well-received by automotive critics, who praised its powerful engine, luxurious interior, and comfortable ride. However, some critics noted the car’s weight and the relatively dated five-speed automatic transmission compared to newer competitors. Fuel economy was also a point of concern, with combined fuel consumption rated at 13.5 l/100 km (17.4 US mpg / 20.9 UK mpg).
Compared to other SL variants, the SL 55 offered a significant performance advantage. It was more expensive than the base SL models but provided a more exclusive and rewarding driving experience. In terms of reliability, the M113 engine is generally considered to be robust, but preventative maintenance, particularly regarding the supercharger and cooling system, is crucial.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | SL |
| Generation | SL (R230, facelift 2006) |
| Type | AMG SL 55 V8 (517 Hp) Automatic |
| Start of production | February, 2006 |
| End of production | February, 2008 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Fuel consumption (urban) | 20.3 l/100 km (11.6 US mpg / 13.9 UK mpg) |
| Fuel consumption (extra urban) | 9.6 l/100 km (24.5 US mpg / 29.4 UK mpg) |
| Fuel consumption (combined) | 13.5 l/100 km (17.4 US mpg / 20.9 UK mpg) |
| CO2 emissions | 324 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 4.5 sec |
| Acceleration 0 – 62 mph | 4.5 sec |
| Acceleration 0 – 60 mph | 4.3 sec |
| Acceleration 0 – 200 km/h | 14 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 113.992 |
| 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 | 9:1 |
| Number of valves per cylinder | 3 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Supercharger, Intercooler |
| Valvetrain | SOHC |
| Engine oil capacity | 8.5 l (8.98 US qt / 7.48 UK qt) |
| Coolant capacity | 13 l (13.74 US qt / 11.44 UK qt) |
| Kerb Weight | 1885 kg (4155.71 lbs.) |
| Max. weight | 2205 kg (4861.19 lbs.) |
| Fuel tank capacity | 80 l (21.13 US gal / 17.6 UK gal) |
| Length | 4532 mm (178.43 in.) |
| Width | 1827 mm (71.93 in.) |
| Height | 1298 mm (51.1 in.) |
| Wheelbase | 2560 mm (100.79 in.) |
| Drive wheel | Rear wheel drive |
| Number of gears | 5 |
| Gearbox type | Automatic transmission |
Legacy
The AMG SL 55 (R230) remains a desirable used car, appreciated for its combination of performance, luxury, and relative reliability. The M113 engine is known for its durability when properly maintained. However, potential buyers should be aware of the need for regular maintenance, particularly regarding the supercharger and cooling system. The car’s value has remained relatively stable, reflecting its enduring appeal and the reputation of the Mercedes-Benz AMG brand. It represents a sweet spot in the R230 SL lineup, offering a significant performance upgrade over the base models without the higher running costs and complexity of the later SL 63 AMG.
