We’re all guilty.

Most cars can go well over the speed limit on freeways and surface streets, and we’ve all been in a rush to get somewhere, at some point.

But aside from being illegal and dangerous, there is a practical reason why experts say drivers should generally avoid speeding.

It doesn’t save much time.

Researchers with the U.S. Army studied the impact of speeding on trip lengths. It found the time you can shave off a trip by speeding isn’t that much to start, and goes down dramatically with in higher speed zones.

The U.S. Army examined how long it takes to drive 15 miles at three different speed limits, and then how much time is saved by going 10 miles per hour over each of those limits, hiroad.com reported.

  • If the speed limit is 35 mph, it takes around 25 minutes to travel 15 miles. If, instead, you go 45 mph, you save about five minutes.
  • If the speed limit is 50 mph, it takes 18 minutes to travel 15 miles. If you were going 60 miles per hour, you would get to the destination three minutes faster.
  • Let’s say the speed limit is 65 mph, it takes just under 14 minutes to travel 15 miles. If you decide to speed and go 75 mph, you’ll get there in 12 minutes – saving around two minutes.

Mathematically, speeding has the biggest impact on longer road trips.

For example, one researcher found that going 65 mph instead of 55 mph over the course of 50 miles will save you about 8.5 minutes.

Of course, heavy traffic, signals, stop signs, weather, and a host of other factors make these examples nothing more than equations and not reality.

For more than two decades, speeding has been a factor in roughly one-third of all traffic fatalities in the U.S., according to the National Highway Traffic Safety Administration. So, safety is the most obvious reason the government doesn’t want us to speed.

But it’s not the only reason.

NHTSA says speeding also lowers fuel efficiency and reduces the effectiveness of car safety equipment, like airbags and brakes. It can also cost a lot if you get ticketed and see your car insurance premiums go up.