A friend has a 350z. I agree with the others that the XFire's interior is better. Yes, it's painted plastic, but it's very nicely painted plastic, and I've had nothing but compliments from friends and family. The other way to look at it is that the plastic is lighter, and saving weight is a good thing in a performance car.

I don't know who thinks the seats are not supportive. They are among the most supportive, stock, that I've experienced, and most of the articles I've read like the seats very much.

The Xfire will lose a drag race to the 350Z. But it's not a drag car. The 350Z would lose a drag race to a Mustang SVT. It's about what you want. I can tell you this, considering the Xfire is a sporty luxo coupe, it is a very remarkable handling car with lateral grip that pleasantly surprised me. It simply goes where you point it.

All that said, it gets down to what you want. Which car pleases you more aesthetically? Which fits you better? Which one's performance characteristics do you prefer?

Remember too, the 350's powerplant is a Renault engine. Nothing wrong with that, but w/the Mercedes engine you're getting something which, although getting a bit long in the tooth, is a solid performer that has long since had the kinks worked out.

Go drive both. Drive the RX8 too. It's a lot of money to drop on a car, be sure about what you want. Enjoy...the process of choosing is fun!