Driving styles vary, so we may not be together on this at all, but I'll try. I don't own any of the MB race cars at the moment; I didn't care for the SLSs at all, and I can't make the Beemer race cars get out of their own way
. I'm not recalling off the top of my head what PPs you're needing for IA events, but I do know I used the Vision MBs quite a bit overall. The race car if I remember was a bit slower but more stable. If you can tune it to brake and corner properly, I seem to remember using the Ford GT500 a lot through the middle of the lineup (meaning between the Sunday Cup stuff and the "endurance" races). I'm sad to say I haven't tried the McLauren/BMW F1 cars either, as the Stealth was one of my favorites in GT5, but the handling/tuning issues in GT6 have so far scared me away from such cars. If you can throw me some PP requirements, and the tracks involved, I might can get more specific.