2001 Audi TT. To be honest, didn't know what to expect from this, but two years and 30,000kms, it's been the most reliable, fun car I've owned. Good all year, once the snow flies it's an absolute riot. Easiest car in the world to take sideways, yet completely liveable everyday. Plus, it'll take a half dozen eight foot sections of 2x6 and still can close the hatch.
For $500, I'm boosting hp from 225 to 260, and torque from 207 to 287 ft-lb. Should be fun.