Study finds obeying speed limits would save 7.2 million gallons of fuel daily, a small share of U.S. total

A study published Thursday found that U.S. drivers could save 7.2 million gallons of fuel and $26 million each day by adhering to speed limits on major roads. University of Minnesota researchers examined 120 million vehicle trips from four Wednesdays in 2021 on roads with speed limits of 45 mph and higher.

More than 43 percent of trips involved at least one instance of speeding, with drivers exceeding limits nearly 12 percent of the time. If light-duty internal combustion engine vehicles followed posted speeds, daily savings would include 57,000 metric tonnes of carbon dioxide emissions, equivalent to removing 5.5 million passenger vehicles from roads.

The analysis showed an average daily driving distance of 28.6 miles would add only 54 seconds when staying at or below limits.

William Northrop, a mechanical engineering professor at the University of Minnesota and study co-author, said: “If your goal is to shave one minute off your time, then you’ve got to drive fast. ” The research also indicated benefits for battery-electric vehicles based on California modeling.

State variations included high speeding in Nevada, Florida, Georgia and North Carolina, while Montana, Wyoming, Idaho and South Dakota showed low prevalence and excess.

Adjusted for 2026 gas prices and vehicle miles traveled, the savings figures rose from the original 2021 estimates of $22 million and 6.7 million gallons. Rob Middleton, associate research scientist at the University of Michigan, called the study well-done but noted the savings represent a small fraction of the 375 million gallons consumed daily in the U.S. drivers face gas prices above $4 per gallon due to the war in Iran.