I think it's nice when a girl knows something about cars. At least this way she knows to at least do basic maintnance on her car to keep it running properly.
I know two girls in my class right now that are into cars. One of them I'm pretty good friend with her and her brother [her brother owns a FCRX7 turbo running mid-13s]. She's pretty cute too.
I find it hot when a girl knows about cars. At least you can talk to her about your hobby and she'll know some of the stuff you're talking about.