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The Mercedes-Benz 300SL Roadster

The Mercedes-Benz 300SL was introduced in 1954 as a two-seat, closed sport car with distinctive gull-wing doors. Later it was offered as an open roadster. It was the fastest production car of its day.

Built by Daimler-Benz AG and internally numbered W198, the fuel-injected road version was based (somewhat loosely) on the company's highly successful competition-only sports car of 1952, the somewhat less powerful carbureted Mercedes-Benz 300SL (W194).

The road model was suggested by Max Hoffman. Being intended for customers in the booming post-war American market it was introduced at the 1954 New York Auto Show, unlike previous models introduced at either the Frankfurt or Geneva shows. In Mercedes-Benz fashion, the "300" referred to the engine's three litre cylinder displacement. The "SL" stood for "Sport Leicht" (Sport Light).

The 300SL was best known for both its distinctive gull wing doors and being the first-ever gasoline-powered car equipped with fuel injection directly into the combustion chamber. The gull wing version was available from March 1955 to 1957. Production of the roadster ended in 1963 with the introduction of the 230SL.

A race car for the street

New York Mercedes distributor Max Hoffman, Daimler-Benz's official importer in the USA, suggested to DBAG management in Stuttgart that a street version of the 300SL would be a commercial success, especially in America.

The racing W194 300SL was built around a tubular chassis to offset its relatively underpowered carbureted engine. Designed by DBAG's chief developing engineer, Rudolf Uhlenhaut, the metal skeleton saved weight while still providing a high level of strength. Its unique architecture gave birth to the model's distinctive gull wing doors, as part of the chassis passed through what would be the lower half of a standard door. Even with the upward opening doors, the 300SL had an unusually high sill, making entry and exit from the car's cockpit problematic. A steering wheel with a tilt-away column was added to improve driver access.

The 300SL's body was mainly steel, except for the aluminum hood, doors and trunk lid. It could also be ordered with an all-aluminium outer skin at tremendous added cost, saving 80 kg (176 lb).

More than 80% of the vehicle's total production of approximately 1400 units were sold in the US, making the Gull wing the first Mercedes-Benz which sold in bulk outside its home market and confirming the validity of Hoffman's suggestion. The 300SL is credited for changing the company's image in America from a manufacturer of solid, but staid, automobiles to that of a producer of sporty cars.

First direct injection

NTX 300 SL Roadster
1955 Mercedes-Benz 300SL Gull wing Coupe from the Ralph Lauren collection
1957 Mercedes-Benz 300SL Roadster.

The 300SL's engine, canted at a fifty-degree angle to the left to allow for a lower hoodline, was the same 3.0 litre straight-6 as the regular four-door 300. Fitted with a Bosch mechanical direct fuel injection system it had almost double the power of the original 86 kW (115 hp) carbureted version.

While not the first fuel-injected car - Mercedes engineers who had developed the principle for the DB 601 fighter aircraft engine had used fuel injection in the tiny 2-stroke Gutbrod they had designed after the War - it was the first to inject fuel directly into the cylinders. This innovation allowed a top speed of up to 260 km/h (161 mph) depending on gear ratio and drag, making the 300SL the fastest production car of its time.

The engine's maintenance requirements were high. Unlike the current electrically-powered fuel injection systems, the mechanical fuel pump would continue to inject gasoline into the engine during the interval between shutting off the ignition and the engine's coming to a stop; this gasoline was of course not burned, and washed the oil from the cylinder walls and ended up diluting the engine's lubricating oil, particularly if the engine was not driven hard enough nor long enough to reach a temperature high enough to evaporate it out of the oil.

Exacerbating the problem were the large oil cooler as well as the large volume of oil (10 liters), both oriented more to racing than to street driving, which virtually guaranteed that the oil would not reach a high enough temperature. In practice, many street drivers would block off airflow through the oil cooler, and the recommended oil change interval was 1,000 miles (1,600 km). Operation of the clutch was initially very heavy, later roadster having an improved clutch arm helper spring which reduced the pedal force. From March 1963 to the end of production, a light alloy crankcase was used on a total of 209 vehicles.

Aerodynamics played an important role in the car's speed, Mercedes-Benz engineers even placing horizontal "eyebrows" over the wheel openings to reduce drag. Unlike many cars of the 1950s, the steering was relatively precise and the four-wheel independent suspension allowed for a reasonably comfortable ride and markedly better overall handling. However, the rear swing axle, jointed only at the differential, not at the wheels themselves, could be treacherous at high speeds or on imperfect roads due to extreme changes in camber.

Original racing history

In 1952, the original 300SL (model Mercedes-Benz W194) scored overall wins at the 24 Hours of Le Mans, in Berne-Bremgarten, in the sportscar race of the Eifelrennen at the Nürburgring, and in Mexico's Carrera Panamericana. It also managed second and fourth places at its first outing, the Mille Miglia in 1952.

These successes, especially those on the high speed open road races, were rather surprising as the engine then was fitted only with carburetors, producing 175 hp (130 kW), which was not only less than the competing cars by Ferrari and Jaguar, but also less than the road car of 1954. Low weight and low aerodynamic drag made the 300SL fast enough to be competitive in endurance races.

Fitch land speed record attempt

In 2005, a 300SL coupe driven by 87 year old John Fitch, who had been a Mercedes-Benz factory racing driver in 1955, attempted to set a new land speed record for the F/GT class at Bonneville Speedway, but was thwarted by a balky fuel pump that limited top speed to 150 mph (240 km/h). After the run, the team vowed to return for a second attempt the next year. Fitch noted that he had driven these cars faster than that at night, in the rain, on the road with 60 other cars. The attempt is documented in the film Gull wing at Twilight: The Bonneville Ride of John Fitch, which was aired on PBS.

The 300SL today

1956 "Gull wing" opened up.

Today, the 300SL with its unique doors, technological firsts, and low production numbers is considered one of the most collectible Mercedes-Benz models of all time, with prices reaching well past the US$700,000 mark. Sports Car International magazine ranked the 300SL as the number 5 sports car of all time. A pair of 300SLs for sale in 2009 were offered at over $1.3M USD from the Foxwood Collection, demonstrating that the price of and demand for this classic remains strong.

The Mercedes-Benz SLS AMG is described by Mercedes as a spiritual successor to the 300SL Gullwing.

Mercedes-Benz still supplies parts for every car they built. Hard to find are the wonderful advertisements from the Classic Center such as this one, where the tag line is: "The Good Old Days with Brand New Parts". The factory also provides some of the best restoration services along with a handful of top-notch independent outfits such as Mercedes-Benz trained 300SL guru Rudiger Koniczek of Rudi & Company in British Columbia, Canada, Paul Russell & Company in Essex, MA, Scott Grundfor in California, Passarelli Restoration in Arizona, in the USA & HK Engineering in Germany.

You'll find several great books about the 300SL along with many reviews and articles to help when looking to purchase a 300 SL Gullwing or Roadster. A short but detailed buyers guide can be found at the Spirited Automobiles blog along with some good photographs.

Technical data