The TVR Cerbera Speed 12, originally known as the Project 7/12, is a high performance sports car designed by TVR in 1997. Based on the TVR Cerbera, the vehicle was intended to be both the world's highest performance road car and the basis for a GT1 class endurance racer. However, problems during its development, changing GT1 class regulations and the eventual decision that it was simply incapable of being used as a road car forced TVR executives to abandon its development. The engine, displacing and having twelve cylinders, was reportedly capable of producing nearly , although an exact measurement was never made. Nonetheless, it was claimed to have a top speed greater than that of the McLaren F1. History Project 7/12 concept The vehicle, known as the TVR Project 7/12, first appeared at the 1996 Birmingham Motor Show and dominated the show once it was unveiled, attracting more crowds than any other cars in the show. The number "7" referred to the 7.7 litre (actually 7.73 L) engine, and "12" for the number of cylinders in the engine. TVR claimed that the engine would have a power output of more than and be faster than the McLaren F1. The first concepts shown were based on FIA GT1 class race rules which meant that they would be restricted to but the weight would be kept at roughly . The road car would weigh the same but without the restrictors, the power was greatly increased. Despite the claims, the actual output figure was not recorded. It had a specially built 6-speed manual transmission and clutch. The engine was essentially made from two TVR AJP6 straight-6 engines mated on a single crankshaft. Unusually for an automobile of its type, the Speed Twelve's engine block was not constructed of cast iron or aluminium alloy, but rather of steel and was designed by John Ravenscroft. Speed 12 GT1 By 1998, the car had been renamed the TVR Speed 12 and the racing version called the Speed 12 GTS was finalising development to compete in the GT1 class races. TVR wanted to race at the 24 Hours of Le Mans, but that never happened. However, the Speed 12 GTS did manage to compete in a few races in the 1998 British GT Championship in the GT1 class, though sudden rule changes caused by advanced high-cost purpose built racers such as the Porsche 911 GT1, Nissan R390