This Group B rally car is designed and built under contract by Williams Grand Prix (Formula 1) engineering. Unlike other rally cars at the time, it is fuel injected rather than turbocharged. Acceleration is zero to sixty in 2.5 seconds. The 6r4 is designed with a normally aspirated v6 engine. It is basically a Rover v8 engine with 2 cylinders removed. The fuel injected motor, as well as the radiators, are mounted at the rear of the car where the back seats would be in a standard MG Metro. This car can achieve 400 horsepower. The 6r4 won one major rally. Just as developments were beginning to make the car successful, Group B rally cars were banned in 1987. The 6r4 continues as a major force in rallycross and hillclimbing where its sheer brute force, light weight, and aerodynamics continue to make it a very competitive car.