Hands down, a Honda S2000. To me, it is an evolution of the S30 (MUCH more so than the 350Z) as it's a raw, firm, minimalist sports car designed for just that. It's not a car based on some econo-car chassis but engineered from the beginning to be what it was going to be, a sports car. It impresses the hell out of me because not only does it perform, but it's also reliable and gets decent mpg!
I've had mine for over a year and I've kept a spreadsheet tracking all costs. I've only done basic maintenance and gas, and I'm averaging 28mpg.