To sum it up: Vehicle behaviour is quite correct, except the lack of ability to search for an effective cover.
However, (un-)mounting troops for ground vehicles (and helicopters?!!) would be VERY helpful for various situations you may want to create with the mission editor (i.e. soldiers defending their vehicles (and themselves), troops brought to the fight/evacuated from a position by trucks, APCs or choppers, SAR,...). A lot of improvement that could be gained by just that one feature!