1985-1989 Mercedes-Benz SL (R107 facelift ) 420 SL V8 (218 Hp) Automatic

The Mercedes-Benz SL (R107) 420 SL V8 Automatic, produced from 1985 to 1989, represents a significant iteration of the iconic SL roadster. This variant, part of the R107 series which spanned from 1971 to 1989, benefited from a 1985 facelift that modernized its aesthetics and refined its engineering. Positioned as a mid-to-upper range offering within the R107 lineup, the 420 SL bridged the gap between the more accessible 300 SL and the high-performance 560 SL, appealing to buyers seeking a blend of luxury, performance, and grand touring capability. The R107 chassis, known for its robust construction and comfortable ride, provided a solid foundation for this powerful V8 engine.

At the heart of the 420 SL lies the M 116.964 4.2-liter V8 engine. This naturally aspirated powerplant featured a single overhead camshaft (SOHC) valvetrain operating two valves per cylinder. Fuel delivery was managed by a multi-port manifold injection system, contributing to smooth power delivery and reasonable fuel efficiency for its displacement. The engine produced 218 horsepower at 5200 rpm and 330 Nm (243.4 lb-ft) of torque at 3750 rpm. This power was channeled through a four-speed automatic transmission, designed for comfortable cruising rather than aggressive shifting. The engine’s longitudinal front-engine layout contributed to a balanced weight distribution, enhancing handling characteristics. The engine’s displacement is 4196 cm3 (256.06 cu. in.) with a bore of 92 mm (3.62 in.) and a stroke of 78.95 mm (3.11 in.). Compression ratio was set at 9:1.

The 420 SL Automatic offered a distinctly different driving experience compared to its manual transmission counterparts or the higher-output 560 SL. While not as overtly sporty, the automatic transmission provided effortless acceleration and a relaxed driving style ideal for long-distance journeys. The 0-60 mph sprint took approximately 8.1 seconds, and it could achieve a top speed of 212 km/h (131.73 mph). The automatic transmission’s gear ratios were optimized for cruising, resulting in a comfortable ride but potentially sacrificing some responsiveness. Compared to the 560 SL, the 420 SL offered a more manageable power delivery, making it less demanding to drive. The 300 SL, with its smaller engine, provided a more economical option but lacked the 420 SL’s substantial torque and overall refinement.

The 420 SL Automatic came standard with a well-appointed interior featuring leather upholstery, power windows, and central locking. The dashboard layout was typical of Mercedes-Benz in the 1980s, emphasizing functionality and understated elegance. Optional extras included air conditioning, a sunroof, and upgraded audio systems. The two-seater roadster configuration prioritized driver and passenger comfort, offering a spacious cabin for its class. The exterior styling, post-facelift, featured smoother lines and integrated bumpers, giving it a more contemporary appearance than earlier R107 models.

The chassis of the 420 SL utilized a coil spring and double wishbone suspension setup at the front, coupled with a threaded twist beam and coil spring arrangement at the rear. A transverse stabilizer bar was included at both ends to reduce body roll during cornering. Braking duties were handled by ventilated discs at the front and solid discs at the rear. The hydraulic power steering provided light and precise control. Tire size was 205/65 VR15 on 7J x 15 inch rims for both front and rear wheels. The kerb weight of 1600 kg (3527.4 lbs) contributed to its stable and predictable handling.

Contemporary reviews of the 420 SL Automatic generally praised its comfortable ride, refined engine, and luxurious interior. Critics noted that the automatic transmission, while convenient, didn’t fully exploit the V8’s potential. Fuel economy was considered reasonable for a vehicle of its size and performance, averaging around 14.6 l/100 km (16.1 US mpg) in urban conditions and 9.3 l/100 km (25.3 US mpg) on the open road. Reliability was generally good, typical of Mercedes-Benz engineering of the era, although maintenance costs could be substantial due to the complexity of the V8 engine and its associated systems. Compared to the 300 SL, the 420 SL offered a significant performance upgrade, while the 560 SL provided even more power but at a higher price point.

Today, the R107 420 SL Automatic remains a desirable classic car, appreciated for its elegant styling, comfortable ride, and robust engineering. While maintenance can be costly, the availability of parts and a dedicated enthusiast community ensures that these vehicles can be kept on the road for years to come. The M 116 engine, when properly maintained, is known for its longevity and reliability, making the 420 SL a rewarding ownership experience for those seeking a classic Mercedes-Benz roadster.