A part of me is considering buying a 2004 Audi A4, 1.8t, Quattro with a boat load of miles (160K). It has service records with the dealership that are rather complete. Would be due for a timing belt in 20K miles, which I would plan on replacing myself. It also needs new window motors/regulators, a new rear door, and the front bumper valance. And it smells like horrible smoke. Obviously, I am prepared to do quite a bit of work on the car and spend some money in the process.

How big of a mistake would this be?