Why Fuel Economy Tanks 25% When You Hit 75 Mph: The Physics Explained






Gas prices, as we all unfortunately know, are volatile, with prices subject to a host of market and geopolitical pressures. This is important for drivers because, depreciation aside, fuel is the second-biggest car ownership cost, behind financing or leasing payments.

While it’s unlikely that many of us whistle with joy as we watch the price display shoot up at incredible speeds, gasoline is a necessary expense, and it’s something we grin and bear. But there comes a point when the cost of fueling your car rises to such a degree that many Americans need to cut costs anywhere they can. 

There are plenty of ways to avoid wasting fuel in your car. Just driving fewer miles is one option, but for some, that isn’t a possibility, so another option is to cover the same miles using less fuel. One way to do this is to reduce the speed at which you drive. The good news is that if you stay within the speed limit, you’re probably okay — according to data from Energy.gov, a mid-sized gasoline-powered car is most efficient at 55 mph. 

However, the same data shows that by the time the car is traveling at 75 mph, it’s burning 25% more fuel than it would if it were traveling at a more sedate 45 mph (32 mpg versus 43 mpg respectively). This is mostly down to aerodynamics and how they’re affected by speed. In short, while aerodynamics can affect the top speed of your car, the underpinning science means aerodynamic efficiency lessens at higher speeds. Let’s put our lab coats on and take a look at the physics of why speeding cars burn more fuel. 

The physics of speed and fuel consumption

Of course, car manufacturers are aware of the effect of aerodynamics in vehicles and how it affects efficiency. However, even with the most streamlined of designs — and we quote from a famous Starfleet engineer of the future here — they “cannae change the laws of physics.”  

More specifically, the effects of aerodynamics and how speed affects fuel economy can be measured using a formula called the drag equation. The details are best left to mathematicians and engineers, but essentially, the equation calculates the resistance or drag force of a vehicle as it moves through the air. It uses variables including a vehicle’s velocity, the air density, drag coefficient (a measure of a vehicle’s aerodynamic efficiency), and the vehicle’s frontal area to work out an overall drag force. 

While all these factors have a bearing on the output of the equation, the one we’re particularly interested in is velocity. In the drag equation, speed is squared, meaning that as velocity increases, aerodynamic resistance increases rapidly. Essentially, this means that even small speed increases require disproportionately more energy — or fuel, if you’d prefer. 

To understand how this works, we can plug the 45 mph and 75 mph figures into the equation and see what happens. Ignoring the other factors and focusing on speed only, we can work out that a car travelling at 75 mph is travelling 1.7 times faster than the slower car. Remembering that speed is squared in the equation, we can square 1.7 to determine that the car faces roughly 2.8 times as much air resistance. The fuel economy hit comes from the power required to overcome that resistance. 





Source link

Leave a Reply

Subscribe to Our Newsletter

Get our latest articles delivered straight to your inbox. No spam, we promise.

Recent Reviews


If Game Two of their first-round playoff series with the Denver Nuggets saved the 2025-26 season for the Minnesota Timberwolves, Game Three showed why it should be saved. 

The Timberwolves were a different beast while decisively thumping the Nuggets, 113-96 Thursday night at Target Center, in a game that wasn’t nearly that close. These Wolves were the mythical creature we’d heard about in preseason lore, purposefully locked and loaded to be both marauding and staunch. They owned both ends of the court, gleefully transferring back and forth from irresistible force to immovable object. 

A quartet of Timberwolves deserve special mention, but it begins with Jaden McDaniels. After his team had toppled Denver to even the series at a game apiece Monday night, McDaniels used the sizable chip on his shoulder to etch some graffiti into the public discourse, casually castigating the most prominent Nuggets players by name as “bad defenders” in a matter-of-fact manner that had the media compelling him to confirm what he had just said. 

Trash talk is fleetingly fungible in the jaundiced social environment of 2026, functioning more like coupons than currency in that it needs to be rapidly leveraged before its expiration date. The common perception naturally was that McDaniels was calling out the Nuggets. But in a more subtle, profound way, he was also putting his teammates on notice. 

All season long the Timberwolves have procrastinated on their full potential, frequently demonstrating that their preseason talk about maturity and commitment was cheap. By contrast, those words uttered by McDaniels were expensive. He had just picked a fight with the opponent, leaving open the question of how many of his teammates would join him in the fray. 

That he would lead the charge was established early, after the Timberwolves’ top two scorers, Anthony Edwards and Julius Randle, had each missed a pair of open looks against Denver’s bad defenders in the game’s first 90 seconds.  

With the game still scoreless, the NBA’s best pick-and-roll combo, Nikola Jokic and Jamal Murray, were clustered around the foul line with Minnesota’s best defenders, McDaniels and Rudy Gobert. As they jammed up Jokic, McDaniels picked the ball loose and started sprint-dribbling the other way. To no one’s surprise, Donte “Ragu” DiVincenzo was also on his horse in transition, receiving a pass from McDaniels and then lobbing it back for a Jaden slam against a hapless Murray and Murray’s late-arriving teammate, Cam Johnson, who committed the foul that allowed McDaniels to finish with the “and-1” free throw. 

On the Timberwolves next offensive possession, McDaniels muscled his way to two offensive rebounds, feeding Ragu off the first one for a missed three-pointer, which he corralled for the second one and executed the putback in traffic. It was McDaniels 5, Nuggets 0, setting the tone for a game in which not only did the Wolves never trail, but never let the lead go under double digits after McDaniels made a consecutive pair of driving layups eight minutes into the game. 

“Spectacular. I thought his activity offensively in the first quarter was outstanding,” said Wolves coach Chris Finch after the game. “He was inspirational.” 

Among the most inspired were McDaniels fellow wing players, Ragu and Ayo Dosunmu. Ragu is exactly the kind of player who will have your back in a squabble, and his galvanized performance seemed borne of satisfaction that someone else had clarified the mission. As usual, the Timberwolves were at their best with him on the court: +20 in the 32:54 he played, -3 in the 15:06 he sat. 

“He makes so many hustle plays, momentum plays, different styles of plays.” Finch raved. “He’ll make a shot, get a transition bucket, he’ll rebound, get a steal, blow something up. So many different plays. He’s just a basketball player.”

Related: How the Timberwolves sparked a season-saving Game 2 comeback over the Nuggets in Denver

Then there was Ayo, whose fearless, blazing, bee-lines for the bucket were quicksilver kryptonite for a Nuggets defense that is neither swift nor rugged. “I’ve been waiting for him to wake up a little bit in this series,” Finch accurately observed. “The downhill mindset that he played with all season for us was back.”

Back with the sort of multipurpose propulsion that leaves witnesses with giddy whiplash. Ayo led the team with 25 points and 9 assists in 32 minutes of time-lapse hoops, the lone blemish being three clanks from long range. Why chuck treys when you can so easily undress players in the paint? Ayo was 10-for-12 on two-pointers and none of those dozen shots came from anywhere but beneath the rim. Five of his nine dimes likewise yielded layups or dunks, which means he personally accounted for 30 of the 68 points in the paint by the Timberwolves on Thursday, doubling up the Nuggets’ 34.

Which brings us to the non-wing in Game 3’s ring of honor, Rudy Gobert. For the third straight game, Gobert blunted the supposed advantage Denver had with the magical playmaker Nikola Jokic at the controls. Suffice to say that in the last five quarters, Jokic has shot 8-for-33 from the floor. If that continues, the Nuggets are toast in this series. 

When I asked Finch after the game if the herculean job Gobert was doing on Jokic made planning his defense simpler and better thus far, he replied, “Rudy is making all of us look good right now with his defense.” 

Amen.

If there is an asterisk on this game, it would be the absence of Denver’s brutishly versatile power forward Aaron Gordon. Nuggets coach David Adelman should be given a lot of credit for his honesty and transparency in dealing with the media during his first full season at the helm, but it came back to bite him and his team during the pregame presser, when he was clearly rattled and dejected by the sudden unavailability of Gordon, whose playing status went to “probable” to “out” in a period of a few hours due to a chronic calf strain. 

Gordon is far and away his team’s best defender, making the timing of his injury especially troublesome in the wake of McDaniels laying down his marker. Rattled is a good way to describe the entire team’s performance in the first quarter, an emotional wounding that needs to heal as fast as Gordon’s body if the Nuggets are going to be competitive in a series that had dramatically been flipped on its head over the past three days. 

That the Timberwolves played with such dominance despite mediocre outings from Ant and Randle would be a good thing for both of those current cornerstones to keep in mind. Ant was beset by foul trouble and Randle had a solid second quarter, but it stood out that neither player fully embraced what so often works on offense when the Wolves are at their best: Push the pace, move the ball, move without the ball, and make quick decisions. Ant and Randle can still be first among equals and blend into that catechism if they stay attuned to the possibilities of a greater good, one that all of sudden doesn’t have to end with them being postseason fodder for the Spurs or the Thunder. 

Not when you’ve got three wings at a collective peak, with a chaser of Rudy semi-clowning the Joker. 



Source link