4th Generation Group 5 – "Special Production Cars" (1976 to 1982)

Forza 6 has a really great selection of cars and in particular the Group 5 cars have really been great fun to drive from the moment I tried the showcase event featuring them and they all sound great, I’d say my favourite at the moment is the Ferrari 512 BB/LM and The Zakspeed Capri comes a close second let down only by the fact it tops out at 170mph meaning you can’t catch the BMW’s.
Does anyone know where I can find more information on the 4th generation Group 5 as so far a few bad video’s on youtube and a tiny bit of info on Wikipedia seems to be all I can turn up after hours searching.

Also which Group 5 car do you prefer and why?

Mine is the 512 BB/LM as mentioned because its speed and handling, the Capri is great but I find it to be harder to tame the tail end even on straights at speed.