you can look at issues like this only emotional, financially none of the cars makes sense.
- looks - both cars are unique
- chick magnet - same status
- financially - keep the Crossfire
- maintenance - buy the BMW. I don't trust the Chrysler guys being able to service a relative complex car
- performance - handling - the Z4 beats the Crossfire hands down with its responsiveness and feel for the limits. The XFires circulating ball stearing box was already used by the Romans for their Chariots.
- and then the engine. The BMW name stands for Bavarian Motor Works and the engines are still way ahead in power delivery, etc.

I know - I own a BMW M5, a Crossfire SRT, a BMW Z1(look up under www.BMW-Z1.de), a P911-994 Cabriolet, a P944, a Alfa Romeo Spider,a VW Beetle Convertible (he real one - not the Golf-based) to judge the minute differences!

Have fun with what you got and if you are after performance - look at the P Cayman!

HJM