It will be a slouch, but with a decent suspension it doesn't mean you can't have fun autocrossing it.
Sorry Ralf I gotta disagree with you this time lol..
320/325 are roughly the same animals in terms of power.
320i is usually just a lot more barebones in terms of amenities and parts. Suspension itself is different and geared towards economy. A few parts on the 320 would be considered second line options when compared to the other non-M e46's
If you wanted a decent track car, with a more raw feel out of the box, I'd say E36 M3.