In the early 1980s, the FIA changed the grouping rules for touring cars, in order to keep them closer to the specification of their road car counterparts. Previously the rules had allowed companies to take advantage of loopholes; for example the FIA rules didn’t specify parts such as headlights had to remain in their standard location – hence 'Flat nose' Porsches. The same went for flared arches and spoilers, and the late 70s saw some impressive displays of aerodynamics, particularly on Group 5 cars.
Before the rule change BMW decided it should go racing with the new E24 6-series to replace the 3.0 CSLs that had raced and won in the European Touring Car Championship. The new 635 CSi Group 2 was born, and while it didn’t appear to be quite as much of a wild child as the Group 5 'Batmobiles' had been, it wasn’t a slouch by any means. With a around 300 bhp and wheels so wide they required additional flared arches to tuck them under the body, the new 635 CSi was a potent contender in the ETCC. This example is currently available from Art & Revs.