According to the U.S. Department of Energy (DOE), aggressive driving (speeding, rapid acceleration and braking) wastes gas. It can lower your gas mileage by roughly 15% to 30% at highway speeds and 10% to 40% in stop-and-go traffic.1
Driver feedback devices can help you drive more efficiently. A recent study suggests that they can help the average driver improve fuel economy by about 3% and that those using them to save fuel can improve gas mileage by about 10%.2
Sensible driving is also safer for you and others, so you may save more than gas money.
Read more about it at the Department of Energy website.