What happens when you strap an F1-sized turbo to a 1980s BMW M3, fit it with four wheel drive, and race it on a half dirt/half tarmac rallycross course? You get what could be the nuttiest E30 ever made.
This is at Brands Hatch back in 1988, when rallycross was filled with rally cars banned from proper stage rally for being too fast. This gives you an example of what that meant.
There's a Group B Metro 6R4, but it can't come close to matching Norwegian Arild Martinsen's M3. That is, whenever Martinsen can get his car to stop incinerating its rear tires.