The Mercedes-Benz 300 SLR (W 196 S) is a two-seat sports racing car that took part in the 1955 World Sportscar Championship before a catastrophic crash and fire at Le Mans later that year ended its domination prematurely. The car was designated "SL-R" (for Sport Leicht-Rennen, eng: Sport Light-Racing), which was later condensed to "SLR". Technically, the W 196 S is based on the W 196 R, but has a slightly different engine, displacing 3 litres. Just as the W 196 R Formula One racer's M 196 R engine, the 300 SLR's M 196 S engine is a direct-injected 3-litre straight-eight engine (but with a 78 mm bore and stroke); its rated power is . The W 196 S's monoposto driving position was modified to standard two-abreast seating, headlights were added, and a few other changes made to adapt a strictly track competitor to a 24-hour road/track sports racer. Two of the nine 300 SLR rolling chassis produced (nicknamed the "Uhlenhaut coupé") were converted into 300 SLR/300 SL hybrids. Effectively road legal racers, they had coupé styling, gull-wing doors, and a footprint midway between the two models. When Mercedes-Benz cancelled its racing programme after the Le Mans disaster, the hybrid project was shelved. Company design chief Rudolf Uhlenhaut, architect of both the 300 SLR racer and the hybrids, appropriated one of the leftover mules as his personal car. Capable of approaching , the Uhlenhaut Coupé was by far the fastest road car in the world in its day. A 1955 Mercedes-Benz 300 SLR Uhlenhaut Coupé has become the most expensive car to ever be sold after being auctioned off for €135 million. The car, previously owned by Mercedes-Benz, was sold by RM Sotheby’s to an unknown collector at the Mercedes-Benz Museum on May 5, 2022. History Name In spite of its name and strong resemblance to both the streamlined 1952 W194 Le Mans racer, and the iconic 1954 300SL Gullwing road car it spawned, 1955 300 SLR was not derived from either. Instead, it was based on the wildly successful 2.5-litre straight-eight-powered 1954–1955 Mercedes-Benz W196 Formula One champion, with the engine, enlarged to 3.0 litres for the sports car racing circuit and designated "SL-R" for Sport Leicht-Rennen (eng: Sport Light-Racing). All were the work of Daimler-Benz's design chief Rudolf Uhlenhaut. Racing record Mercedes team driver Stirling Moss won the 1955 Mille Miglia in a 300 SLR, setting the event record