The Mercedes-Benz SL (R129) underwent a significant facelift in 1998, and among the most potent variants produced during the latter years of its run was the AMG SL 73 V12. Production of this high-performance roadster spanned from April 1999 to May 2001, representing the pinnacle of engineering for the R129 generation, which itself was built on the 129 platform. The SL 73 was positioned as the ultimate, no-compromise version of the SL, offering unparalleled power and luxury within the model range.
AMG SL 73 V12: Powertrain & Engine Architecture
The heart of the SL 73 is the M120 E 73 engine, a naturally aspirated 7.3-liter V12. This engine, bearing the code 120.990, is a marvel of engineering, producing 525 horsepower at 5,500 rpm and a substantial 750 Nm (553.17 lb-ft) of torque at 4,000 rpm. The engine boasts a displacement of 7,291 cm³ (444.92 cu. in.) with a bore of 91.5 mm (3.6 in.) and a stroke of 92.4 mm (3.64 in.). It features a compression ratio of 10.5:1 and utilizes a dual overhead camshaft (DOHC) valvetrain with four valves per cylinder.
Fuel delivery is managed by a multi-port manifold injection system. The engine’s longitudinal front-mounted layout contributes to its balanced weight distribution. The M120 engine is renowned for its robust construction and over-engineering, designed for both high performance and long-term durability. The engine requires premium gasoline.
The SL 73 is exclusively paired with a five-speed automatic transmission. This transmission was specifically calibrated to handle the immense power and torque output of the V12 engine. While not offering the driver engagement of a manual gearbox, the automatic provides smooth and relatively quick shifts, prioritizing effortless cruising and grand touring capabilities. The transmission’s gear ratios are tuned for strong acceleration, but also for relaxed highway driving.
Comparison to Other R129 Variants
Compared to other R129 SL models, such as the SL 320, SL 500, and even the earlier SL 600, the SL 73 represents a significant leap in performance. The SL 320 and SL 500 were positioned as more accessible entry points to the SL range, prioritizing fuel efficiency and comfort over outright speed. The SL 600, with its 6.0-liter V12, offered substantial power, but the SL 73’s larger displacement and revised engine management system resulted in a considerable power advantage. The SL 73 was aimed at a buyer who demanded the absolute best, willing to sacrifice some fuel economy for unparalleled performance and exclusivity.
Driving Characteristics
The driving experience in the SL 73 is characterized by effortless power and a refined ride. The 7.3-liter V12 delivers a broad torque curve, providing strong acceleration in any gear. The 0-60 mph sprint is achieved in approximately 4.6 seconds, and the electronically limited top speed is 250 km/h (155.34 mph). Despite its size and weight, the SL 73 feels surprisingly agile, thanks to its well-tuned suspension and responsive steering. The automatic transmission, while not as engaging as a manual, provides smooth and seamless gear changes, contributing to a relaxed and comfortable driving experience. The sheer presence of the V12 engine, with its distinctive exhaust note, adds to the overall sense of occasion.
Equipment & Trim Levels
The AMG SL 73 came standard with a comprehensive list of luxury and performance features. The interior was typically appointed with high-quality leather upholstery, often in exclusive color combinations. Standard features included automatic climate control, power-adjustable seats with memory function, a premium sound system, and burl walnut wood trim. Optional extras included upgraded audio systems, a telephone system, and various customization options through the Mercedes-Benz designo program, allowing buyers to personalize their vehicle with unique interior and exterior finishes.
Chassis & Braking
The SL 73 utilizes a robust chassis designed to handle the immense power of the V12 engine. The front suspension features coil springs, a hydro-pneumatic element, wishbones, and a transverse stabilizer. The rear suspension employs a hydro-pneumatic element, independent multi-link suspension, a transverse stabilizer, and coil springs. This suspension setup provides a comfortable ride while maintaining excellent handling characteristics.
Braking duties are handled by ventilated discs on all four wheels, coupled with an Anti-lock Braking System (ABS) for enhanced safety. The braking system is designed to provide strong and consistent stopping power, even under demanding conditions. The steering system is a cone worm with recirculation balls, providing precise and responsive steering feel, assisted by hydraulic power steering.
Market Reception & Comparison
The AMG SL 73 was widely praised by automotive critics for its exceptional performance, luxurious interior, and overall refinement. However, its high price tag and substantial fuel consumption limited its appeal to a relatively small segment of the market. Fuel economy figures are notably low, with combined consumption reaching 15.9 l/100 km (14.8 US mpg, 17.8 UK mpg, 6.3 km/l). Compared to the SL 600, the SL 73 offered a significant performance upgrade, but at a considerable premium in cost. Reliability was generally good, benefiting from the robust engineering of the M120 engine, although maintenance costs were significantly higher due to the complexity of the V12 powertrain.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | SL |
| Generation | SL (R129, facelift 1998) |
| Type | AMG SL 73 V12 (525 Hp) Automatic |
| Start of production | April, 1999 |
| End of production | May, 2001 |
| Engine Model/Code | M 120 E 73/120.990 |
| Engine displacement | 7291 cm3 (444.92 cu. in.) |
| Number of cylinders | 12 |
| Power | 525 Hp @ 5500 rpm |
| Torque | 750 Nm @ 4000 rpm (553.17 lb.-ft. @ 4000 rpm) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 4.8 sec |
| Acceleration 0 – 60 mph | 4.6 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Kerb Weight | 1975 kg (4354.13 lbs.) |
| 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 | 1296 mm (51.02 in.) |
| Wheelbase | 2515 mm (99.02 in.) |
| Number of gears and type of gearbox | 5 gears, automatic transmission |
Legacy
The AMG SL 73 V12 remains a highly sought-after collector’s car today. Its rarity, combined with its exceptional performance and luxurious appointments, has ensured its continued desirability. The M120 engine is renowned for its durability, and well-maintained examples can provide years of reliable service. However, maintenance costs remain high due to the complexity of the engine and the limited availability of specialized parts. The SL 73 represents a unique chapter in Mercedes-Benz history, embodying the brand’s commitment to engineering excellence and uncompromising luxury. It stands as a testament to the R129 generation’s enduring appeal and its place as one of the most iconic roadsters of its era.
