Most realistic driving physics?

I'm not really into simulators, but I do like physics to be as realistic as possible.

So according to your personal experiences, what engines and games have the most realistic onroad + offroad physics regarding driving:

1. cars / 4-wheel vehicles?
2. motorbikes / 2-wheel vehicles? (realism of this seem to be more problematic for most engines)
3. big / 4 or more wheel vehicles?