A car in which you take care of more then your girlfriend. Do things with the car more often then girlfriend and spend more time with car then girlfriend.
Examples may include waxing washing and car several times a day, staring for long amounts at a time, mentioning the car in most of sentences said in a conversation, reffering to the car as "baby" or "honey" or"she/her", having a cover for said car, putting a prop up tent for said car, etc
A:What's all this on your car?
B: Have to make sure my baby doesn't get scratched
A:Aren't you supposed to meet your girlfriend soon at the movies?
B: What? Who?
A:I think you're too attached to your "girlfriend car"