"Also, if your cheap car is working fine, why would you be in a hurry to buy a new one?"
Great question that everyone struggling with rebuilding credit should ask themselves. I did. My decision was to buy [for cash] a 1993 Buick Roadmaster after haveing driven Porsche 911s for years. It was strange driving that boat for a while but then I started to feel that it was cool and it got a lot a peoples' attention. When I went to register the Roadmaster, the DMV guy [who knew me wll] said to me "Man ...I know there's got to be a story behind this but I will not ask.". My reply was "Rebuilding my credit has become more important to me than the type or car that I drive." Now I own and drive two beautiful Mercedes ... one paid cash for and the other financed and I plan to drive both for many years to come.
If it is the right thing to do, then it is the cool thing to do. That's my motto now.