The Mercedes-Benz 500 SEC, part of the C126 series facelift produced from September 1985 to September 1987, represented the pinnacle of luxury coupe performance for its time. Positioned as the flagship of the S-Class coupe range, the 500 SEC featured a potent 5.0-liter V8 engine paired exclusively with a four-speed automatic transmission. This variant occupied the top tier of the C126 coupe lineup, offering a significant performance upgrade over the 300 SEC and 420 SEC models. The C126 generation, introduced in 1985 as a replacement for the earlier W116 coupes, was a significant step forward in terms of technology, safety, and overall refinement, solidifying Mercedes-Benz’s reputation for building world-class grand tourers.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | S-class |
| Generation | S-class Coupe (C126, facelift 1985) |
| Type (Engine) | 500 SEC V8 (245 Hp) Automatic |
| Start of production | September, 1985 |
| End of production | September, 1987 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Coupe |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (economy) – urban | 15.4 l/100 km (15.3 US mpg, 18.3 UK mpg, 6.5 km/l) |
| Fuel consumption (economy) – extra urban | 9.1 l/100 km (25.8 US mpg, 31 UK mpg, 11 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 7.3 sec |
| Acceleration 0 – 62 mph | 7.3 sec |
| Acceleration 0 – 60 mph | 6.9 sec |
| Maximum speed | 230 km/h (142.92 mph) |
| Weight-to-power ratio | 6.6 kg/Hp, 151.2 Hp/tonne |
| Weight-to-torque ratio | 4.1 kg/Nm, 246.9 Nm/tonne |
| Power | 245 Hp @ 4750 rpm |
| Power per litre | 49.3 Hp/l |
| Torque | 400 Nm @ 3750 rpm (295.02 lb.-ft. @ 3750 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 117 E 50 / 117.965 |
| Engine displacement | 4973 cm3 (303.47 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 96.5 mm (3.8 in.) |
| Piston Stroke | 85 mm (3.35 in.) |
| Compression ratio | 9:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | SOHC |
| Engine oil capacity | 9 l (9.51 US qt | 7.92 UK qt) |
| Coolant | 13.5 l (14.27 US qt | 11.88 UK qt) |
| Kerb Weight | 1620 kg (3571.49 lbs.) |
| Max. weight | 2140 kg (4717.89 lbs.) |
| Max load | 520 kg (1146.4 lbs.) |
| Fuel tank capacity | 90 l (23.78 US gal | 19.8 UK gal) |
| Length | 4935 mm (194.29 in.) |
| Width | 1828 mm (71.97 in.) |
| Height | 1407 mm (55.39 in.) |
| Wheelbase | 2845 mm (112.01 in.) |
| Front track | 1555 mm (61.22 in.) |
| Rear (Back) track | 1527 mm (60.12 in.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 4 gears, automatic transmission |
| Front suspension | Double wishbone |
| Rear suspension | Threaded twist beam |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic Steering |
| Tires size | Front wheel tires: 205/65 R15 Rear wheel tires: 205/65 R15 |
| Wheel rims size | Front wheel rims: 7J x 15 Rear wheel rims: 7J x 15 |
Powertrain & Engine Architecture
The heart of the 500 SEC was the M117 E 50 engine, a 4.97-liter (303.47 cubic inches) naturally aspirated V8. This engine, a cornerstone of Mercedes-Benz’s engineering prowess, featured a cast-iron block and aluminum cylinder heads. It utilized a single overhead camshaft (SOHC) design with two valves per cylinder. Fuel delivery was managed by a Bosch K-Jetronic multi-port fuel injection system, known for its reliability and precise metering. The M117 engine was renowned for its smooth power delivery and robust construction. The engine produced 245 horsepower at 4750 rpm and 295 lb-ft of torque at 3750 rpm. Paired with the engine was a four-speed automatic transmission (typically the 722.3 series), designed for smooth and comfortable shifting. This transmission, while not offering the performance of a manual, was well-suited to the grand touring nature of the 500 SEC.
Driving Characteristics
The 500 SEC offered a distinctly different driving experience compared to its six-cylinder siblings. The V8 engine provided ample power for effortless cruising and brisk acceleration. The 0-60 mph sprint was dispatched in around 6.9 seconds, and the car could reach a top speed of 143 mph. While the automatic transmission wasn’t geared for outright performance, it provided smooth and refined shifts. The gear ratios were optimized for comfortable highway driving, with a focus on relaxed cruising rather than aggressive acceleration. Compared to the 300 SEC or 420 SEC, the 500 SEC felt significantly more responsive and capable, particularly when overtaking or climbing hills. The added power and torque made it a more confident and enjoyable grand tourer.
Equipment & Trim Levels
The 500 SEC came standard with a comprehensive list of luxury features. Leather upholstery was standard, as were power-adjustable front seats with memory function. Climate control, a premium sound system, and power windows and locks were also included. The interior trim was typically finished in wood veneer, adding to the car’s luxurious ambiance. Optional extras included a sunroof, heated seats, and a more advanced audio system. The 500 SEC was positioned as the top-of-the-line model, and as such, it received the highest level of standard equipment.
Chassis & Braking
The C126 coupe chassis featured independent suspension all around, with a double wishbone setup at the front and a threaded twist beam at the rear. This suspension configuration provided a comfortable ride while maintaining good handling characteristics. The 500 SEC was equipped with ventilated disc brakes at the front and solid disc brakes at the rear. An Anti-lock Braking System (ABS) was standard, enhancing safety and control during hard braking. The steering was a recirculating ball system with hydraulic power assistance, providing a comfortable and precise steering feel.
Market Reception & Comparison
The 500 SEC was generally well-received by automotive critics. It was praised for its powerful engine, luxurious interior, and comfortable ride. However, some critics noted that the automatic transmission wasn’t as engaging as a manual gearbox. Compared to the 300 SEC and 420 SEC, the 500 SEC offered a significant performance advantage, but it also came with a higher price tag. Fuel economy was also lower with the V8 engine, averaging around 15.4 l/100 km in urban driving and 9.1 l/100 km on the highway. Despite the higher running costs, the 500 SEC was considered a worthwhile investment for those seeking a truly luxurious and capable grand tourer.
Legacy
The M117 engine, found in the 500 SEC, is known for its durability and longevity. With proper maintenance, these engines can reliably exceed 200,000 miles. The C126 coupe, including the 500 SEC, has become a sought-after classic car, appreciated for its elegant styling and engineering excellence. Today, well-maintained examples command high prices in the collector car market. The 500 SEC represents a high point in Mercedes-Benz’s history, embodying the brand’s commitment to luxury, performance, and engineering quality. Finding parts can sometimes be a challenge, but a dedicated network of suppliers and enthusiasts ensures that these cars can be kept on the road for years to come.
