We're still pissed at the Forza Motorsport kids for not having a 2CV in the game. This must change, and it must change immediately and without compromise. Right now they're in the midst of dyno pulls for the second edition of the racing sim, and they've posted a bit about having an '88 M6 on the dyno. It's got an oversize straight six and makes about 460 ponies at the crank, which isn't exactly something to sneeze at. It's also unavailable for road use.
Turn 10 Dyno Spotlight: Eric Brannfors' 1988 BMW E24 M6 Monster [Forza Motorsport]
Microsoft's Forza Motorsport for Xbox: The Missing Cars [Internal]