The way I see it is this, you will have to insulate your anode from your cathode, else you will have a dead short and lots of burnt wires and blown fuses, so there is no path for current to flow. No electrons can move. They are stuck. Now if you immerse your car in a meduim like salty water, a small amount of current (electrons) can flow though the water and complete a circuit. In open air no current can flow and you just end up with an incomplete circuit. It will do nothing.