My SRT I'm all about performance. Who buys a sports car (well, a sporty sport compact) and then cares about gas mileage? Pay to play.
My Cavalier, all about mileage. It's my work car and I just want A to B.
My wife's Patriot, both. It's underpowered and the CVT trans sucks. A little extra power helps (especially for me as I drive it to work sometimes, merging SUCKS). But for her any extra mileage works. We average 27.8mpg (first 3500 miles), no complaints.
Performance for me as well, my first big turbo setup was a gt35r 750cc injectors and on a trip down 81 I was able to get 302 miles on one tank of gas. Car was making around 423 at that time but of course I made myself not hit to boost just to see how much I could actually squeeze out of a tank. Im sure others have gotten more this is just my experience