Unfortunately, I was told by an officer that if someone is blocking you by standing in the way, your only option is basically waiting until they move, unless you can get them to move. If you attempt to move them with your car, it is assault.
That can change quickly once they begin to act in a way that a reasonable person would believe put them in danger of imminent bodily harm...or something along those lines.
Who had the quote about use of force being the same whether you used a gun or a weedeater...or a Chevrolet.