The Mazda RX-8 would be a mistake. They are underpowered, particularly for a car that is heavy and almost sedan-like. Last I heard, evidence indicated that the car did not make even the meager official horsepower specs, so Mazda probably overrated it. Also as THX mentioned, this engine burns way too much fuel for such low power output.
The Z is not a bad car, but I guess it\'s a matter of personal taste. I disliked them from the beginning, and now I have to look at them everywhere. The Japanese Mustang. Certainly you can say with certainty that the build quality is not up to the standard of other competitive manufacturers, including Honda & Toyota.
Why don\'t you consider a used Subaru Impreza or a Civic Si?