R&T decided to test a Gullwing 300SL in 1968 to see how it compared to contemporary cars. It had been the leading edge sports car of its time, but time stands for no car, especially back then, when automotive evolution ran a bit faster.
The 300SL may have been the fastest production sports car in 1955, but the 1957 Corvette with its new fuel injected 283 V8 easily spanked it in all of the performance stats. The Corvette clicked off the 0-60 run in 5.7 seconds, compared to 8.2 for the 300SL; in the 1/4 mile, the ‘Vette ran a blistering 14.3 seconds to the Gullwing’s 16.0. Of course the Corvette’s engine was about 50% larger in displacement, but then it also cost about 50% less. Obviously the Corvette’s refinement was not in the same league, especially when the road got a bit rough. The 300SL’s direct injected 3 liter six was rated at 240 hp; the 283 at 283 hp (both SAE gross ratings).
As to top speed, the 300SL was touted to do 146 mph, but back in 1955 when R&T tested one, they only got it to 134 mph. Since we’re also looking at the Corvette, it managed 132 mph with very steep 4.11:1 rear axle gears. With the right gears, it could do 150.
The 300SL’s four wheel independent suspension with swing axles on the rear rode firmly, but was not jarring, and would compare well with current GT cars, better than some over rough roads. Its handling was deemed to fall short of 1968 standards though. The steering was quick, but the swing axles made themselves known, and “you’d better be ready for it”. The camber changes combined with the narrow wheels and tires resulted in “miserable low cornering power”; a turn that the the 300SL might get through at 35 mph a Lamborghini Miura might do at 50 mph. The tires alone were a big factor.
The giant finned drum brakes weren’t too bad, but obviously not up to 1968 standards for world-class sports/GT cars.
The driving position was considered to still be quite good, but the cockpit heat was excessive, which resulted in the not-uncommon practice of its owners driving around town with the doors open. Seriously.