Why is my new 09 Yaris MPG is so low

[Yaris Hilton]

Originally Posted by LittleRed

i get 40+ with the a/c on most of the time

So will mine, driving steadily out on the highway. But different driving situations will make a big difference. Stop and go driving wastes a lot of energy. Wind has a big effect. On average you won't come close to gaining back from tailwinds what you lose to headwinds. And as you drive faster, your aerodynamic drag goes up roughly as the square of your speed. Headwinds and crosswinds affect you far more as you drive faster. Your local terrain will have an effect, too. You'll never do as well in hilly country as on the flatlands. You burn more gas climbing hills than you save coasting down them.