I think the real question on all of our minds...
Do hookers count?
But seriously...
Here's what ya do, matey: You cant just not do anything, then she'll say you were just doing nothing to get free repairs, and you cant go get another girl. Women might be hard to understand, but if there's one thing I've learned from them it's that they never what you to do what they actually say they want you to do, unless the thing they say they want you to do is "Take out the trash." So, you must do something completely different. Try! Yes, try, and fully fail. Try hard to fail. How, you ask? Like this! Go to bars with your current girl so she can see you try to "hook up" with another babe. Pick girls who are the same attractiveness level of your current girl (trust me, that's a whole 'nother road of pain) and use lines like "You have boobs. I like that in a woman." Or "We can mate in 176 different ways. Care to learn how?" So long as you're out of earshot when you make these statements, your current girl will feel sympathy (and jealousy) as you're slapped, spat on, had drinks thrown on you, kicked in the nuts, etc. Not only will you lose the bet (winning new truck parts) but your girl will feel sorry for having put you in that place in the first place. That is, the place of setting you up to fail.
So. Listen to my wisdom, and go forth, be the worst ladies' man that ever walked this green earth, and you shall find your reward soon.