Technically speaking it's not a man who has sex with cars. As I'm one such I know my subject. An autophile is in love with him or herself sexually. So
I'm stuffed for a good word to use (apart from the often heard, insane, crazy, etc). The only alternative I've heard is automobiliphilia. Quite a mouthful, more than the gearknob of a Jaguar
XJ8 so probably won't be popular. There probably should be two words. One for a person who loves his car
on every level and has it as a substitute totally for a human partner and one for a man who simply fucks it.