The Mercedes-Benz SL 500 V8 (455 Hp) with the 9G-TRONIC PLUS automatic transmission represents a high-performance iteration of the R231 SL-Class roadster, produced from May 2019 through 2020. This variant arrived as part of the R231’s facelift, introducing updated styling, improved technology, and refined powertrain options. Positioned as a premium offering within the SL lineup, the SL 500 V8 bridged the gap between the entry-level SL 450 and the more potent AMG variants, appealing to buyers seeking a blend of luxury, performance, and grand touring capability. It was built on the Mercedes-Benz M231 platform.
Powertrain & Engine Architecture
At the heart of the SL 500 V8 lies the M278.927 engine, a 4.7-liter, V8 gasoline engine. This engine is characterized by its twin-turbocharged configuration, employing a single turbocharger per cylinder bank. This bi-turbo setup, coupled with intercooling, delivers a substantial 455 horsepower at 5250 rpm and 700 Nm (516.29 lb-ft) of torque between 1800 and 3500 rpm. The engine utilizes direct fuel injection, optimizing combustion efficiency and power output. The valvetrain is a double overhead camshaft (DOHC) design, featuring four valves per cylinder, contributing to the engine’s responsiveness and high-revving nature.
The 9G-TRONIC PLUS automatic transmission is a nine-speed automatic gearbox designed to enhance both fuel efficiency and driving dynamics. It features a wide gear ratio spread, allowing the engine to operate within its optimal power band more frequently. The transmission offers multiple driving modes, including Comfort, Sport, and Manual, allowing the driver to tailor the shift points and responsiveness to their preferences. Paddle shifters are also included for manual gear selection. The transmission is longitudinally mounted, driving the rear wheels.
Engine Specifications
The M278.927 engine boasts a compression ratio of 10.5:1. It features a bore of 92.9 mm (3.66 in) and a stroke of 86 mm (3.39 in), resulting in a displacement of 4663 cm3 (284.55 cu. in). The engine also incorporates a Start & Stop system to improve fuel economy during city driving and a particulate filter to reduce emissions, meeting Euro 6d-TEMP-EVAP-ISC standards.
Driving Characteristics
The SL 500 V8 delivers a refined and powerful driving experience. The twin-turbocharged V8 provides strong acceleration, with a 0-60 mph time of approximately 4.1 seconds and a 0-100 km/h time of 4.3 seconds. The 9G-TRONIC transmission contributes to smooth and seamless gear changes, enhancing both comfort and performance. The wide gear ratio spread allows for relaxed cruising at highway speeds while providing quick downshifts for overtaking maneuvers. Compared to the SL 450, the SL 500 V8 offers a noticeably more potent power delivery and a more engaging driving experience. While not as aggressively tuned as the AMG variants, the SL 500 V8 provides ample power for spirited driving and confident highway performance. The rear-wheel drive configuration contributes to a balanced chassis and predictable handling.
Equipment & Trim Levels
The SL 500 V8 came standard with a comprehensive array of luxury features. Interior appointments typically included high-quality leather upholstery, wood or aluminum trim, and power-adjustable seats with memory function. Standard technology included a large infotainment display, navigation system, premium sound system, and a suite of driver-assistance features such as adaptive cruise control, lane-keeping assist, and automatic emergency braking. The SL 500 V8 was often equipped with features like the AIRSCARF system, which directs warm air onto the occupants’ necks, enhancing open-top driving comfort. Optional extras included upgraded leather packages, advanced driver-assistance systems, and personalized interior customization options.
Chassis & Braking
The SL 500 V8 utilizes an independent multi-link suspension system at both the front and rear axles. This suspension design provides a comfortable ride while maintaining precise handling characteristics. The chassis is constructed with a combination of aluminum and steel to minimize weight and maximize rigidity. The braking system features ventilated discs at all four corners, with front discs measuring 360 mm and rear discs measuring 320 mm. The system is equipped with ABS (Anti-lock Braking System) and electronic brake-force distribution for enhanced safety and control. The steering system is an electric power steering rack and pinion, providing precise and responsive steering feel.
Market Reception & Comparison
The SL 500 V8 was generally well-received by automotive critics, who praised its powerful engine, refined ride, and luxurious interior. It was often lauded as a sweet spot in the SL lineup, offering a compelling balance of performance and comfort. Fuel economy, while not a primary focus for this type of vehicle, was considered reasonable for its class, with combined fuel consumption ranging from 10.3 to 10.7 l/100 km (22.8-22 US mpg). Compared to the SL 450, the SL 500 V8 offered a significant performance upgrade, justifying the higher price tag for buyers prioritizing power and acceleration. However, the AMG variants provided even more extreme performance for those seeking the ultimate driving experience. Reliability reports suggest that the M278 engine is generally robust, but regular maintenance is crucial to prevent potential issues with the turbochargers and fuel system.
Technical Specifications
| Body type | Roadster, 2 Doors, 2 Seats |
| Fuel economy | 10.3-10.7 l/100 km, 22.8 – 22 US mpg, 27.4 – 26.4 UK mpg, 9.7 – 9.3 km/l |
| CO2 emissions | 236-237 g/km |
| Acceleration 0-100 km/h | 4.3 sec |
| Acceleration 0-60 mph | 4.1 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Engine Power | 455 Hp @ 5250 rpm |
| Engine Torque | 700 Nm @ 1800-3500 rpm (516.29 lb.-ft. @ 1800-3500 rpm) |
| Engine Displacement | 4663 cm3 (284.55 cu. in.) |
| Number of Cylinders | 8, V-engine |
| Fuel Injection System | Direct injection |
| Engine Oil Capacity | 8 l (8.45 US qt | 7.04 UK qt) |
| Kerb Weight | 1740 kg (3836.04 lbs.) |
| Max. Weight | 2175 kg (4795.05 lbs.) |
| Trunk Space (min/max) | 364 – 485 l (12.85 – 17.13 cu. ft.) |
| Fuel Tank Capacity | 75 l (19.81 US gal | 16.5 UK gal) |
| Length | 4631 mm (182.32 in.) |
| Width | 1877 mm (73.9 in.) |
| Height | 1315 mm (51.77 in.) |
| Wheelbase | 2585 mm (101.77 in.) |
| Gearbox | 9 gears, automatic transmission |
Legacy
The SL 500 V8 (R231) represents a compelling blend of performance, luxury, and technology within the SL lineage. While the R231 generation was discontinued in 2020, the SL 500 V8 remains a desirable vehicle in the used car market. The M278 engine, when properly maintained, is known for its reliability and longevity. However, potential buyers should be aware of the maintenance requirements associated with a turbocharged engine, including regular oil changes and inspection of the turbochargers and cooling system. The 9G-TRONIC transmission has also proven to be generally reliable, but fluid changes should be performed according to the manufacturer’s recommendations. Overall, the SL 500 V8 offers a sophisticated and rewarding driving experience, making it a popular choice for enthusiasts seeking a grand touring roadster.
