The best mileage I've gotten with this car is 48 mpg. That was on a cross-country trip. This mileage was just fairly short runs. I think using gas with no additives is one reason my mileage is good. It doesn't hurt that the car itself, a Honda Civic, is gas-thrifty. Another thing that helps my mileage is accelerating calmly. Also, if I know I'm about to encounter a stop sign or traffic signal, I don't pass people to get to it.