The biggest diference is of course the number of seats !! :P
4 for the BMW & Mazda, 2 for the Crossfire.

I did not even try the BMW 325i when I was looking for my new car. Mainly because this is not the same spirit as the two others (You won't have so much fun driving a BMW 325i). Moreover, you can see BMW everywhere here in Europe

Mazda RX8 (the 231Hp or the 193hp): the engine did a so special noise when I test it (like a aeroplane!) due to this bi-rotor system, it was so cool hh (I did 7500 RPM !). I appreciate the quality of materials (for mazda) and the 4 seats. But the RX8 looks like a tuning car, I don't like that. (specially the rear, face is quite aggresive, like it)

Crossifre: can be compared with Nissan 350Z for the fun you can get with (even the automatic transmission). Xenons ? you don't really need as lights are so beautiful on the basic Xfire
6CD loaders : my local Chrysler answered me no but you can do it by yourself, and you need space ... which is quite rare in the Xfire