Apart from the crackpot-that-disproves-current-phyics factor, I won't comment on that since I'm not a physicist, there's still the issue of conservation of energy. The antenna might be really large, but any energy received must be transmitted somewhere, I doubt that your average AM radio station is set up for this. If an electrical car uses around 1kW (probably much more), how many cars are there within the area of such an antenna? Tuning an (electrically) huge antenna to an AM radio station would probably kill the reception. He also mentions that you have to get the antenna further off the ground for these frequencies, probably not that practical on top of a car.