>"Come to think of it, when it comes to cars and plumbing, I suspect Nick is probably next to useless."

I think that the presence of the under-repair motorcycle in Nick's living space is supposed to suggest to us that he is working on its engine himself. (My father is a motorcycle fancier, and he tells a story of his first year married to my mother, when she came home to find he'd disassembled his motorcycle in their tiny apartment to work on it, and he thought it was fine because he'd put down sheets first...)

But of course we never do see Nick work on the motorcycle — or even ride it, only very occasionally sit on it — much less on the Caddy. Fanon assumes that Nick takes the Caddy to mechanics; I don't think I've ever read a suggestion that he does more than fill its gas tank himself.