CRZ is too much, nevermind. I am a huge fan of the GTO, the look of them doesn't bother me any. People make fun that it looks like a slipper, lol, but I do not think it looks bad. I didn't think the Zs were great with fuel, but for power and handling it is the best bang for the buck. I know the GTO beats the Z in power, but the Z takes handling, and reliability.
Whatever you get, before mods, you should be seeing highway mpgs for the tank if it is standard and you drive conservatively. I am not saying no GTO, for the price range it seems good, just to not forget about the Z. The handling in tuns, quality, and should put it in the ball park of the GTO.
EDIT:
For 10k, I found a 2004 GTO and 28 Zs from 2003-2007 within 500 miles of me.
Cd is .30 for the Z.
http://www.cars.com/go/compare/model...8962,6268,2819
Your choice is your choice, but the more I look into it, the more it seems the Z is the way to go. Cheaper, newer, everything mentioned before. Either way you go, I look forward to see the results