It may feel more satisfying to fly around other drivers on the highway, but the joke is on you. Your gas mileage will decrease rapidly after your speedometer hits 60 miles per hour and higher, and boost your travel costs.
In addition, rapid acceleration and braking also can reduce your gas mileage. Driving at a lower speed can help you save as much as 33 percent on your cost to fill up at the pump, says Jody DeVere, chief executive at AskPatty.com, an automotive advice and education site for women.
"Observing the speed limit is also safer, so you may save more than just money," DeVere says.