I've been really enjoying racing in Automobilista 2 with several friends recently. A bunch of us went from using a controller to having a wheel and often a wheel stand in a short period of time, because we all got so into it.
I think there is a lot going for AMS2 (as it is commonly abbreviated): lots of variety in the cars and tracks, it is easy to set up casual races with friends, it is very dynamic (like in varying track and weather conditions), works well with a controller or a wheel, looks good and performs well, etc.