Based on the TVR Cerbera, the vehicle was intended to be both the world's fastest road car and the basis for a GT1 class endurance racer.

The engine, displacing 7.7 L (469.9 cu in) and having twelve cylinders, was reportedly capable of producing nearly 1,000 hp (746 kW), although an exact measurement was never made.

The first concepts shown were based on FIA GT1 class race rules which meant that they would be restricted to 660 hp (492 kW) but the weight would be kept at roughly 1,000 kg (2,205 lb).

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.

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 and the Toyota GT-One and the subsequent demise of the class in other championships suddenly rendered the Speed 12 obsolete.

[4] In order that their work not go to waste, TVR immediately set about developing the road-going Speed 12, although the project would not be completed for another year.

The weight was kept down to 1,000 kilograms and TVR reminded people that they were making a car that they thought would beat the McLaren F1 with the words "over 240 miles per hour" mentioned on several occasions.

In an interview then-owner Peter Wheeler, said that TVR had tried to record the car's power on an engine dyno.