My commute is only 10 miles round trip, so this is not something I am considering, but have a few friends who have gone through this thought process and have owned versions of some of the more frequent suggestions to your question.
One friend, who had a 110 mile round trip commute, was tired of his pick-up's gas bill, so he got a Ford Focus. I can't remember what he was getting, but he was one happy person after the first tank of gas lasted him longer than 2 days. His entry point was high because he bough it new, but 6 years later, it still hums along without many issues.
I personally have owned a '86 Civic Wagon and a CRV, back to back. The CRV with Real-Time 4x4 only got about 17.5 mpg in the city. So, I'd go with the small, fuel efficient car over anything else if it were me.
I think a Toyota Corolla or a Honda Civic are about as good as you're going to get if durability and gas mileage are important. If you are looking for something cheaper (to buy) look at Nissan or Kia. Even Subaru makes good cars; all depends on what you want, what you like and what you can find used and in good shape.