Speeding Saves Almost No Time but Costs Billions
The Myth of the Minute
For decades, drivers have pressed the accelerator with a simple belief: speeding gets them there faster. A new study published in the journal Communications Sustainability shatters that assumption with hard data. Researchers at the University of Minnesota analyzed 120 million vehicle trips across the United States from four Wednesdays in 2021. They used driving data on national road networks, speed limits, and U.S. Geological Survey elevation data. The analysis included roads with speed limits of 45 mph (72 kph) and higher. The result is clear: the time saved by speeding is negligible.
The study found that more than 43% of the studied trips included at least one instance of speeding. Drivers spent nearly 12% of their driving time going faster than the speed limit. Yet the payoff was minimal. With an average daily driving distance of 28.6 miles (46.03 kilometers), driving at or below the posted limit corresponds to only about 54 seconds longer per day. That is less than one minute. For most commuters, the time saved by speeding is less than the time spent waiting at a single red light.
William Northrop, a mechanical engineering professor at the University of Minnesota and a study co-author, put it directly. “If your goal is to shave one minute off your time, then you’ve got to drive fast,” he said. “If your objective is to get to your destination safely and to save fuel, then you might drive slower than the speed limit.” The research challenges a deeply ingrained habit. Many drivers believe that speeding is essential for punctuality. The data shows that belief is largely false.
The Hidden Cost of Pressing the Pedal
The study also quantified the financial and environmental waste. If drivers of light-duty, conventional internal combustion engine vehicles actually drove at posted speed limits, it could save an average of $22 million per day based on fuel costs at the time. That daily savings translates to 6.7 million gallons of fuel and 57,000 metric tonnes of carbon dioxide every day. The researchers said that is comparable to taking about 5.5 million passenger vehicles off the road. The scale is enormous.
Driving faster increases a vehicle’s energy use and the emissions from its engine. It also reduces efficiency. Vehicle engines have become increasingly more efficient over the past several decades, even as vehicles have gotten bigger and more powerful. But speed limits have also climbed since the Emergency Highway Energy Conservation Act was implemented. That act mandated 55 mph national speed limits amid the 1970s energy crisis. The current study shows that the gains from modern engine efficiency are partially undone by higher speeds.
The cost has only grown. Accounting for the average cost of gas today and more vehicle miles traveled, the potential savings increase to roughly $26 million and 7.2 million gallons of fuel that Americans collectively could save each day this year just by not putting the pedal to the metal. The study also modeled battery-electric vehicle efficiency using California data, reflecting the state’s higher EV adoption rate at the time. Based on the California modeling, Northrop said, “We find that driving slower is beneficial for EVs as well.” The principle applies across vehicle types.
The Unresolved Contradiction
The study revealed interesting geographic differences. Nevada saw elevated speeding prevalence as well as high speed excess. There was high speeding prevalence in Florida, Georgia, and North Carolina, though those states did not necessarily exhibit high speed excess. Montana, Wyoming, Idaho, and South Dakota showed both low speeding prevalence and speed excess. The reasons for these differences are not fully explained by the data. Why do drivers in some states speed more than others, even when the time savings are equally small?
One limitation of the research is that slower driving could impact traffic patterns, which could play a role in efficiency. If everyone drove the speed limit, traffic flow might change in ways that are not yet understood. The study did not model those effects. The contradiction remains: the individual benefit of speeding is tiny, yet the collective cost is massive. Drivers continue to speed, wasting billions in fuel and emitting millions of tons of CO2, all for less than a minute of time saved per day. The study leaves open the question of how to close the gap between individual behavior and collective benefit