You've gotten some sound advice here. I did it for a few years and it's fun but expensive (though much less so than real racing). The Vibe really isn't terribly well-suited to autocrossing. I would go so far as to say that's especially true for the GT because they base the class designations on (peak) power-to-weight ratio, so the peaky power curve would be a disadvantage. If you just want to go out and have fun and learn about controlling your car at the limits, though, there's no cheaper way outside of donuts in the parking lot.Personally, I recommend attending an autocross school if your region has one (I learned a LOT there), or going to a Porsche Club of America High Speed Driver's Education. Both of these will be more expensive than autocrossing (the Porsche Club one is a lot more), but having somebody who knows what they are doing ride with you and/or take you around the track is absolutely invaluable. Porsche club one is a lot of fun because you're on a real track and the speeds are high. There is more potential for damage to your car, but wheel-to-wheel racing is strictly verboten and I haven't seen many incidents (in fact none spring to mind at all).