360 miles on a tank of gas? I used to get over 400 miles on a tank of gas, my car has 50,000 miles on it, I just had the oil and filter changed mobil 1 5w20, and all my tires are properly inflated. I've had all my required maintenance done at the Honda dealership. What could be causing my drop in fuel economy? I don't drive my vehicle hard, the last time I had the air filter changed was in June of 2010.