Let's not forget that mileage is made or broken not on the highway going a steady 55, or 65, or 85... It takes a beating on the acceleration, idling, stop and go, etc that it takes to get to the highway and in stop and go traffic. If you're heavy on the gas and brake, your mpg is going to suffer. So take it easy out there, pick a speed, stay with it and forget about weaving in and out of traffic all over the freeway just to get to point B a minute quicker. Keep your RPMs to a minimum and enjoy the ride