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Bill Vance: 300SL's iconic gullwing doors were an engineering solution

The Mercedes-Benz 300SLs left an indelible impression because it had everything -- advance engineering, outstanding performance and and the cachet of those iconic doors
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A 1954 Mercedes Benz 300SL. The car, now a very sought after and expensive collectible, made its debut at the New York Auto Show in February, 1954. BILL VANCE

Daimler-Benz and German rival Auto-Union had been almost invincible on the 1930s Grand Prix racing circuits. But the Second World War’s devastation took its toll and by the early 1950s D-B still wasn’t financially or technically able to return to Grand Prix competition. Auto Union ended up in East Germany.

Daimler-Benz, manufacture of Mercedes-Benz cars and trucks, took until 1951 to introduce its first all-new post-war 220 and 300 sedans. With modern passenger models in production the company felt ready to pursue some of its pre-war racing glory.

As an interim step to the new open-wheel Formula 1 series it chose sports car racing by creating a sports racer using M-B 300 sedan parts. The 300 was not a racing car but its engine, driveline and chassis components were robust enough for competition.

The 3.0 litre (183 cu in.) single overhead camshaft 12-valve, short-stroke, inline six had a sturdy, forged, fully counterweighted steel crankshaft rotating in seven generous main bearings.

To accommodate these mechanicals an aluminum bodied coupe with a low 0.25 coefficient of aerodynamic drag was created. It was designated the 300SL (for 3.0 litres, Sport and Light).

Since the sedan frame was too heavy for competition a bridge-like “space frame” was fabricated from small diameter tubes. This strong, light frame extended halfway up the sides of the car, preventing using regular doors. The designers, therefore, placed the door-bottoms at mid-level and extended the tops into the reinforced roof and hinged them near the middle of the car. The doors rose vertically like wings.

Quickly dubbed gullwing doors, they were the 300SL’s most striking and imitated feature. An engineering solution had turned into an iconic styling signature.

The high, wide sills made entry and exit awkward so the steering wheel tilted down to aid access. Once inside, it was snug and comfortable compared with open sports cars, and the all-round visibility was excellent.

The 300 sedan’s 2,996 cc modestly stressed engine produced just 115 horsepower at 4,600 rpm but was sturdy enough to reliably develop more than double that; the production 300SL was was rated at 240 horsepower.

Carburetors were used during development but production model got Bosch mechanical fuel injection, the world’s first four-stroke, gasoline-engine production car with this feature. It also got racing-type dry-sump lubrication, and to clear the low hood the engine was tilted 50 degrees to the left.

The 300SL quickly made its mark in competition, winning, among others, the 1952 Le Mans, France, 24-hour race and Carrera Panamericana (Mexican Road Race). It also excelled in rallying.

After pointing the way to D-B’s return to Grand Prix racing, the 300SL would likely have been relegated to D-B’s museum like other M-B racers but for the intervention of Mercedes-Benz’s New York-based American distributor, Max Hoffman.

Hoffman was America’s imported car czar, a man with a keen marketing sense. His Manhattan dealership sold everything from Volkswagens to Rolls-Royces.

Hoffman became a Mercedes distributor in 1952, and when he saw the Mercedes-Benz 300SL sports racing car he knew it would sell in America. He implored D-B to make it a production model, backing up his conviction by ordering 1000 of them. It was an opportunity too good for D-B to pass up.

The production Mercedes-Benz 300SL gullwing coupe, and less potent four-cylinder 190SL convertible, made their debut at the New York Auto Show in February, 1954. The 300SL was a sensation with the public and motoring press. Production began that summer.

The 300SL fulfilled its performance promise. Road & Track (4/55) reported the 1,229 kg (2,710 lb) coupe accelerated from zero to 97 km/h (60 mph) in 7.4 seconds, and to 161 (100) in just 17.2 seconds. It reached a top speed of 225 km/h (140 mph).

R&T called it “…the ultimate as an all-round sports car,” concluding that “The sports car of the future is here today.”

The 300SL had a hefty price — some $8,000 — a lot of money when a new Cadillac could be had for $5,000. This, in part, is probably why only 1,400 gullwing coupes were produced from 1954 to ‘57.

It was replaced by the 300SL roadster with a frame modified to allow conventional doors, and with D-B’s low-pivot rear swing axle assembly replacing the traditional swing axles. Four-wheel disc brakes came in 1961, and the roadster remained in production until 1963; 1858 were built.

The Mercedes-Benz 300SLs left an indelible impression because it had everything. Fuel injection was a significant engineering advance. And it had outstanding performance, impeccable racing credentials and the cachet of those gullwing doors, which M-B more recently reincarnated in its SLS model.

The 300 SL is one of history’s great automobiles, even though it was not originally intended for production. It has become a very sought after and expensive collectible.

bvance1@cogeco.ca