IsaacCarlson is asking the right question here; what you need will define what is a good car. I consider my Corolla, currently getting ~45mpg, good. But one of my "needs" was an automatic tranny (my wife has never driven a stick and has no real desire to do so). I'm pretty sure I'd be in the ~50mpg range if I had the manual tranny. Are you mechanically savvy? If so, that greatly increases your possibilities.
When I search the garage for gasoline cars over 45mpg lifetime,
I find a wide assortment of vehicles. (And that doesn't include diesels!) Yes, you see a lot of Civics and Metros, but also a fairly broad assortment of others.
You can find a bunch of great mpg machines for ~$2k. You have to do a lot of looking, but they are out there. Craigslist in my area had me drooling over two listings: a civic vtec engine and a miata that I'd love to do a "
Jack McCornack" on.