Mercedes-Benz SL engines

Since its launch in 1954, the Mercedes-Benz SL model series has stood for sporty elegance and technical excellence in the roadster segment. Over seven generations, an impressive range of engines has been developed, from classic naturally aspirated engines to ultra-modern V8 biturbo units. The technological evolution of Mercedes-Benz SL engines has always reflected the current state of automotive technology.

Mercedes-Benz SL engines: Historic generations I-III (1954-1989)

The first three Mercedes-Benz SL generations shaped the legend of the model series and established standards for sports cars worldwide. The R107 generation (1971-1989) easily reached 400,000 to 500,000 kilometers with proper maintenance, while the legendary 300 SL "Gullwing" of the R198 generation (1954-1963) is considered indestructible today. Major engine damage was extremely rare in these robust designs. The absolute top engine of the historic generations was the 6.3-liter V8 in the 300 SEL 6.3, which was also used in the SL - a power unit that combined power and reliability in perfect harmony. The R113 generation (1963-1971) with its characteristic "pagoda roofs" brought modern safety technology and refined chassis with it for the first time.

Mercedes-Benz SL petrol engines: Historic generations I-III (1954-1989)

The early Mercedes-Benz SL engines initially included the legendary 3.0-liter in-line engine in the 300 SL (R198) with 158 kW (215 hp) and fuel injection - an absolute sensation for the 1950s. The R113 generation brought smaller engines such as the 2.3-liter six-cylinder (110-125 hp) and the 2.8-liter engine (130-170 hp). The Mercedes-Benz SL R107 revolutionized the model series with a wide range of V8 engines: the 3.5-litre V8 (200 hp), 4.5-litre V8 (225 hp) and the mighty 5.6-litre V8 (300 hp) set new standards. These Mercedes-Benz SL engines were characterized by their exceptional longevity - mileages of over 500,000 kilometers were not uncommon, only the valve stem seals required attention every 200,000 kilometers.

Mercedes-Benz SL engine comparison table: Historic generations (1954-1989)

Mercedes-Benz SL Generation IV (1989-2001)

The R129 generation marked the transition to the modern era and is considered one of the most reliable Mercedes-Benz SL generations ever. With proper maintenance, most engines easily reach 300,000 to 400,000 kilometers, with the V8 units being particularly durable. Major repairs are typically only due after 200,000 kilometers, usually limited to wearing parts such as the water pump or air conditioning compressor. The absolute highlight was the 6.0-liter V12 in the SL 600 - a technical masterpiece with 290 kW (394 hp), which offered both power and smooth running to perfection. This generation was the first to introduce modern safety technology such as the automatic roll bar and ASR traction control and positioned itself against competitors such as the Porsche 911 Convertible and BMW 8 Series.

Mercedes-Benz SL petrol engines: Generation IV (1989-2001)

The Mercedes-Benz SL R129 engine range started with the tried-and-tested 3.0-liter in-line engine (SL 300) with 140 kW (190 hp), which proved to be extremely reliable. The Mercedes-Benz SL 320 received a 3.2-liter V6 with 170 kW (231 hp), while the V8 variants included the SL 500 with 4.2 liters and 235 kW (320 hp) and later with 5.0 liters and 240 kW (326 hp). These Mercedes-Benz SL engines were considered virtually indestructible - only the ignition coils of the V8 units tended to fail after 150,000 kilometers. The Mercedes-Benz SL 280 (from 1993) with a 2.8-liter V6 and 142 kW (193 hp) developed into the entry-level model, but occasionally exhibited problems with the head gasket when the engine overheated.

Mercedes-Benz SL V12 engine: Generation IV (1989-2001)

The Mercedes-Benz SL 600 with its 6.0-liter V12 (M120) and 290 kW (394 hp) represented the absolute pinnacle of the R129 generation. This Mercedes-Benz SL engine combined impressive performance with exceptionally smooth running and proved to be surprisingly reliable. Typical weak points were only the complex electronics and occasional problems with the fuel pump, otherwise the V12 was considered one of the most durable Mercedes engines ever.

Mercedes-Benz SL Generation V (2001-2012)

The R230 generation brought a completely new direction with an innovative vario-roof and state-of-the-art electronics, but proved to be less reliable than its predecessor. Mileage dropped to between 200,000 and 300,000 kilometers, with complex electronic systems often requiring costly repairs after just 100,000 kilometers. The revolutionary Vario roof developed into the biggest weak point of the generation - hydraulic problems and seal damage were frequent. The best engine was the 5.5-liter supercharged V8 in the SL 55 AMG with 368 kW (500 hp), which remained surprisingly reliable despite its high output. This generation competed directly with the Porsche 911 Turbo Cabrio and BMW 6 Series Convertible, but was not entirely convincing due to electronics problems.

Mercedes-Benz SL petrol engines: Generation V (2001-2012)

The Mercedes-Benz SL R230 series started with the SL 350 and its 3.5-liter V6 with 180 kW (245 hp), which proved to be a solid entry-level engine. The Mercedes-Benz SL 500 initially received a 5.0-liter V8 with 225 kW (306 hp), later a 5.5-liter V8 with 285 kW (387 hp). These Mercedes-Benz SL engines suffered from the typical problems of the M113/M273 engine family: mass air flow sensor failures, defective ignition coils and, in the case of the V8 units, occasional problems with the camshaft phasers. The Mercedes-Benz SL 280 with 3.0-liter V6 and 170 kW (231 hp) was considered the most reliable engine of this generation, but sometimes showed weaknesses with the valve cover gasket.

Mercedes-Benz SL AMG engines: Generation V (2001-2012)

The AMG variants set new performance standards: The Mercedes-Benz SL 55 AMG with 5.5-liter supercharged V8 and 368 kW (500 hp) and the later SL 63 AMG with 6.2-liter V8 and 386 kW (525 hp). The absolute highlight was the Mercedes-Benz SL 65 AMG with 6.0-liter V12 biturbo and 450 kW (612 hp). Despite their extreme performance, these Mercedes-Benz SL AMG engines proved to be surprisingly durable; only the supercharger clutch of the SL 55 AMG tended to wear out after 120,000 kilometers.

Mercedes-Benz SL Generation VI (2012-2020)

The R231 generation marked a return to proven technology with a soft top instead of a vario-roof and focused on driving dynamics and reliability. Mileage increased again to 250,000 to 350,000 kilometers, with the new biturbo V8 engines becoming significantly more efficient. Major repairs are typically only due after 150,000 kilometers, mostly on wearing parts such as turbochargers or injection nozzles. The top-of-the-range engine was the 4.0-liter V8 biturbo in the SL 63 AMG with 430 kW (585 hp) - a technical masterpiece that optimally combined performance and efficiency. This generation introduced extensive lightweight construction measures for the first time and successfully positioned itself against the Porsche 911 Turbo S Cabrio and Aston Martin DB9 Volante.

Mercedes-Benz SL petrol engines: Generation VI (2012-2020)

The Mercedes-Benz SL R231 engine range initially comprised the SL 350 with a 3.5-liter V6 and 225 kW (306 hp), which impressed with its modern direct injection and lightweight construction. The Mercedes-Benz SL 400 received a 3.0-liter V6 biturbo with 245 kW (333 hp), while the SL 500 was equipped with a 4.7-liter V8 biturbo with 320 kW (435 hp). These new-generation Mercedes-Benz SL engines proved to be significantly more reliable than their predecessors - only the direct injection occasionally tended to coke up the intake valves. The Mercedes-Benz SL 300 (from 2016) with 2.0-liter four-cylinder turbo and 180 kW (245 hp) developed into the most problematic engine of this generation with frequent turbocharger damage and oil consumption problems.

Mercedes-Benz SL AMG engines: Generation VI (2012-2020)

The AMG variants relied on modern biturbo technology: the Mercedes-Benz SL 63 AMG started with a 5.5-liter V8 biturbo and 390 kW (530 hp), but was later replaced by the 4.0-liter V8 biturbo with 430 kW (585 hp). The Mercedes-Benz SL 65 AMG retained the 6.0-liter V12 biturbo with 463 kW (630 hp). These Mercedes-Benz SL AMG engines were regarded as the brand's most reliable high-performance units, with only the turbochargers requiring occasional attention after 120,000 to 150,000 kilometers.

Mercedes-Benz SL Generation VII (2021-today)

The current R232 generation represents a complete reorientation as a 2+2-seater and relies exclusively on state-of-the-art biturbo technology with mild hybrid support. All Mercedes-Benz SL engines have a 48-volt on-board electrical system and electric assistance, which significantly increases efficiency. As the generation has only been available since 2021, no long-term experience is yet available, but the first 50,000 kilometers show promising approaches for mileages of over 300,000 kilometers. The top-of-the-range engine is the 4.0-liter V8 biturbo in the SL 63 S AMG with 430 kW (585 hp), which raises both performance and efficiency to new heights thanks to mild hybrid technology. This generation competes directly with the Porsche 911 Turbo S Cabrio and Ferrari Roma Spider.

Mercedes-Benz SL petrol engines: Generation VII (2021-today)

The Mercedes-Benz SL R232 series starts with the SL 43 AMG and its 2.0-liter four-cylinder biturbo with 280 kW (381 hp) plus mild hybrid system. The Mercedes-Benz SL 55 AMG gets a 4.0-liter V8 biturbo with 350 kW (476 hp), while the SL 63 S AMG tops the range with the same engine but 430 kW (585 hp). These Mercedes-Benz SL engines benefit from the latest AMG technology with electric assistance - initial experience shows significantly improved reliability compared to their predecessors. The Mercedes-Benz SL 43 AMG is shaping up to be the most balanced engine of this generation with its combination of performance, efficiency and expected longevity.

Mercedes-Benz SL mild hybrid technology: Generation VII (2021-today)

All Mercedes-Benz SL engines of the R232 generation feature an integrated 48-volt mild hybrid system with up to 15 kW (20 hp) of electric assistance. This technology not only reduces fuel consumption by up to 0.8 liters per 100 kilometers, but also relieves the combustion engine at low engine speeds, which should significantly increase its service life.

Conclusion: The best Mercedes-Benz SL engines of all generations

The development of Mercedes-Benz SL engines shows a fascinating journey from classic naturally aspirated engines to ultra-modern biturbo units with electrification. While the historic V8 engines of the R107 generation impressed with their indestructibility, the modern AMG biturbo units set new standards in terms of performance and efficiency. With its mild hybrid technology, the latest generation promises an optimum balance between performance and reliability.

• Best Mercedes-Benz SL petrol engine:

The 4.0-liter V8 biturbo (SL 63 AMG, Generation VI) combines 585 hp of power with surprising reliability and moderate complexity.

• Best Mercedes-Benz SL long-distance engine:

The 5.6-liter V8 (R107, Historic Generation) is considered indestructible and easily reaches 500,000 kilometers of mileage.

• Best Mercedes-Benz SL mild hybrid engine:

The 2.0-liter biturbo with EQ Boost (SL 43 AMG, Generation VII) offers 381 hp with high efficiency and state-of-the-art technology.

For maintenance and spare parts for all Mercedes-Benz SL generations, AUTODOC offers a comprehensive range of original and quality spare parts with fast delivery.