Actually, I was the one who said he should mod the Cavvy, but I didn't realize it was a base 4dr. On the other hand, it would make a hell of a sleeper....
As it is, it's a great little commuter. If I had a long commute, I'd probably go for that.
Figure out what kind of fun you want from your car before you buy. If you just want to drag, get an F-body, a Mustang, or just about anything with a small-block Chevy, 5.0, 4.6, or just about any MOPAR V8.
If you want to autoX or road-race, you need to do a lot more research.