During the time I lived in Seattle, there was an autocross almost every weekend thanks to three different available sites. The X is the perfect car to have fun with at autocrosses. If you haven't tried it, do it now, even if you think your car isn't up to it!

While I have done lots of autocrossing (at the amateur level), I did only one hillclimb, at the Oregon Fiat Meet 2000.
While this was a lot of fun, I don't think it is a good use for a car that absolutely needs to stay in one piece. I would build a dedicated car if I wanted to do this regularly.