Question Author
Good answer Minter, however, two points;
1) Never ever assume that someone will help the old man (when you assume, you make an ass out of U + me)
2) You have no idea what the occupants of the car will do, they may be armed with a baseball bat, knife, or something worse like a pistol. There may be more than one occupant, more that you could fight off. best to try and get the number plate and allow the Police to deal with it, that's what they get paid for