I bought a 2008 Yaris in January. I now have 13000 miles on it. Originally I was running the speed limit on all roads, Interstate included and was getting 33-35 and was pretty disappointed. I was talked into dropping down to 65 on Interstate and keeping to the speed limit on side roads. My mileage jumped to a range of 38-43. I still use the ac, but keeping the rpms below 3k was a huge boost in my mileage.