Two units of the Mercedes-Benz 300 SLS, a special variant of the 300 SL Roadster, were built for the American sportscar championship in 1957, due to the fact that the series-production version of the brand-new model was not yet permitted to join the starting line-up of the “standard production” category in the 1957 season.
In order to have at least some chance of success in the only other remaining racing category D, the engineers applied every trick in the book to strip out a standard-production roadster and turn it into the lightweight SLS, weighing just 970 kilograms. At the same time its engine output was increased to 173 kW (235 hp). Paul O’Shea drove the SLS to victory in category D of the American sportscar championship, winning by a clear margin ahead of the competition – so adding to his wins of 1955 and 1956 in the 300 SL “Gullwing”.
After Mercedes-Benz retired their highly successful 300 SLR program, many racing teams and amateur drivers started creating their own versions from the 300 SL production cars. These became known as the SLS and most were prepared with a wide variety of modifications. One of the most famous of these is the Porter roadster which was actively campaigned in America.
Chuck Porter used a wrecked 300 SL Gullwing to create his own SLS. A new body was designed out of his body shop in Hollywood, California and executed by Jack Sutton from .064 aluminum sheet. For the most part, the body stayed faithful to the Mercedes-Benz styling. It featured a much wider front opening, no windscreen, removed doors and a custom interior.
Despite working from a fire-damaged hulk, Porter persisted with the SLS. After it was done, the car was considerably taller than the SLR, since the production SL is much taller than the SLR’s grand-prix chassis. This didn’t stop it from keeping up with the fastest cars in its class with drivers like Ken Miles, Billy Krause and Porter himself.
The car was used from 1956 until 1962, later being fitted with a few different American V8s. Throughout this colorful career, the Porter Special challenged even the Ferraris and Maseratis of the period. This was possible even though the engine was pretty much stock except for a factory performance camshaft.
Sports Car Illustrated tested the Porter SLS against a factory aluminum-bodied 300 SL Coupe and found the SLS to be considerably faster. In 1999 the car was restored by HK-Engineering and subsequently raced at the Monterey Historic Races.