2003 Ford Mustang GT Deluxe 2dr Coupe (4.6L 8cyl 5M)
OK I've only had my license for 4 years but I've owned and test driven quite a few cars. By far this is the best and funnest car, for the price, I've ever had. So far all I have had to replace was the battery and the alternator which for me was super easy and took like 5 minutes total in labor. So far I have only put on a short shifter, BBK cold air intake, MAC off road mid-pipes, and an SLP loud mouth cat-back on it, but I hope to do more soon. The worst gas mileage I have ever gotten with this car was 18 mpg city and that's before the mods, which now I never see below 20 mpg city even if I race it and highway is at about 28 mpg being relatively nice to the throttle!
Power, looks, of course the sound, the MACH 1000 is pretty good for a stock sound system with two 10" subs in the trunk, and the satisfaction of destroying most cars in a race that come up against me.
Better seats and upgraded the suspension, but that's about all I can think of.