I have found that whit the recent addition of setTowParent it generally doesn't really work that well.
What i mean by that is that you need a vehicle just as big in order to tow it.
And you need a run up in order to get it to move.
And then when you get it to move the speed is limited or has jerky reaction.
I find it weird i can't move a panther with a hemtt. When no brakes are engaged because of setTowParent command.