I've been playing the older cars, Ford Escort, Lotus 25, Lotus 49 on all terrain tyres on the RX tracks...so much fun. Found out RX cars don't have headlights when I tried to race in blizzard at night in them, that was tricky lol.
Don't know about the way more grip in wet than dry thing, I'm always slower in wet conditions, how much varies by track and car as some cars seem to have a better balance in the wet. I've never been quicker than in the dry though. I still play AC occasionally, the new Ferrari pack had some nice toys, they really need to sort out the UI to work in VR though.