With everyone worried about gas prices and thieves drilling into gas tanks, we started thinking about the most fuel-efficient used cars on the market (after we determined that building a Nukchero meant risking ball cancer). After all, who wants to spend their hard-earned dollars on a new car when a quality used one can be yours with little to no effort and very little cash from your pocket. Because mileage estimates differ, we used FuelEconomy.org for cars built after 1985 and MPGomatic for older cars. And to prove this isn't just a philosophical discussion, we've actually gone ahead and done the hard work, finding examples of each of these cars for sale. Right now. Check them out below, then go ahead and make a bid! If your favorite is already sold, help your fellow car-loving brethren out by searching for another and providing the results in the comments below.