The MG Metro 6R4 Group B rally car was developed for Austin Rover by Williams Grand Prix Engineering. Named 6R4 due to its 6 cylinder, rear engine and 4 wheel drive. The 6R4 project was launched in 1984 and scored its first rallying victory at the Gwynedd Rally in March 1985.

This is chassis 001, the prototype tested and raced by Tony Pond. It differs from the full Group B version in aerodynamics and having a cut down Rover V8, as the intended unit was still under design.

In May 1985 the full homologation Group B 6R4 was revealed. Fitted with a purpose-built 410 bhp, V6, four OHC, 24-valve engine with four-wheel drive and 60 mph could be reached in 4.3 seconds.