I´m still not sure what size tank I have. The salesman said it was 4.8, and my manual does say 5.3. However, whenever I put gas in it (premium 91+ octane) when the indicator light comes on, I never can add more than about 3.5 gallons, therefore, I think it has a 4.8 gal tank. I´ve been getting 52 - 58 mpg, how are the rest of you doing?