Imagine driving to work tomorrow and barely noticing any extra time on your arrival — but saving money at the pump and cutting pollution at the same time. New research from the University of Minnesota suggests that's not just possible, it's what already happens when drivers stick to the speed limit.
The study, published in the journal Communications Sustainability, analyzed 120 million vehicle trips across the United States using driving data from four Wednesdays in 2021. The researchers looked at roads with speed limits of 45 mph and higher, and they found something surprising: more than 43 percent of trips included at least one instance of speeding, and drivers spent nearly 12 percent of their driving time going faster than the law allows. Yet all that rushing barely gets anyone anywhere faster.
For the typical driver covering 28.6 miles per day, obeying posted speed limits would add only about 54 extra seconds to the commute, the researchers found. Fifty-four seconds. That's barely enough time to change the radio station. But those 54 seconds of patience could save the country 6.7 million gallons of fuel and 57,000 metric tonnes of carbon dioxide every single day, the study estimates. At the fuel prices at the time, that translated to $22 million in daily savings. Researchers said the emissions reduction alone is comparable to taking 5.5 million passenger vehicles off the road entirely.
"If your goal is to shave one minute off your time, then you've got to drive fast," said William Northrop, a mechanical engineering professor at the University of Minnesota and a co-author of the study. "If your objective is to get to your destination safely and to save fuel, then you might drive slower than the speed limit."
The findings come as gas prices remain a pain point for many American households, with a gallon of fuel costing more than $4 in some areas this year. Researchers noted that if you account for today's average gas prices and the fact that Americans are driving more miles overall, the potential daily savings could be closer to $26 million and 7.2 million gallons of fuel. That's a lot of fill-ups, simply by easing off the accelerator.
The researchers also looked at whether electric vehicles might benefit from slower driving. Based on modeling in California, where EV adoption is highest, the team found that driving slower benefits electric vehicles too, since higher speeds reduce efficiency in those vehicles as well.
The study did have limits. Slower speeds could affect traffic patterns in complex ways that the research didn't fully account for. And obviously, drivers sometimes need to speed up to merge onto highways or pass slower vehicles for safety reasons. But taken as a whole, the message is clear: the rush isn't really saving anyone much time — but it is costing us fuel, money, and a cleaner atmosphere.