Speeding and Your Vehicle's Mileage

The Biggest Gasoline Waster - Excess Speed!!

Speeding may be the fastest way to get from Point A to Point B, but it's not a very fuel-efficient solution.

While each vehicle reaches its optimal fuel economy at a different speed (or range of speeds), gas mileage usually decreases rapidly speeds above 55 miles per hour. Just slowing down from 65 mph to 55 mph can increase your miles per gallon by as much as 15 percent.

According to the U.S. Department of Energy (DOE), as a rule of thumb, you can assume that each 5 mph you drive over 60 mph is like paying an additional $0.21 per gallon for gas (at $3.00 per gallon).

So, the Fuel Economy Benefit of driving slower is between 7 and 23 percent. The equivalent gasoline savings is $0.21 to $0.71 per gallon.


Let's take two hypothetical drivers, Bill and Bob. They need to go 60 freeway miles from City A to City B. Both cars get 30 miles per gallon if the driver stayed at 55 mph, the posted speed limit.

Bill travels at 55, but Bob speeds and does 75 mph - wanting to get there sooner.

At 75 mph, it would take Bob about 48 minutes to reach the destination.
At 55 mph, it takes Bill about 65 minutes to reach the destination.

At 55 mph, Bill used 2 gallons of gasoline. At $2.80/gallon, that's $5.60 to drive the distance.
At 75 mph, Bob would use 2.5 gallons of gasoline. At $2.80/gallon, that would be $7.00 to go the same distance.


But it cost Bob $157.00 and he got there AFTER Bill! WHY?

Bob was ticketed for speeding! $150 is the average speeding ticket in the U.S. And if he had been going 80 or higher the fine could have been even more, and he may have had to appear before a judge, cited for reckless driving and even ended up spending some time in jail.

What they should have done is carpooled; saving money, a ticket and gasoline!


Other Things to Think About

Don't be an aggressive driver. The freeway is not a NASCAR race. Speeding, quick lane changes, fast acceleration, and rapid braking all waste gas - and curb mileage by as much as 33 percent at highway speeds, according to the DOE. Instead, keep a steady, constant speed. Use the cruise control where appropriate and safe.

Another reason to not speed is that you may live longer. Speeding is a factor in 31 percent of all fatal crashes, killing an average of 1,000 Americans every month, according to the National Highway Traffic Safety Administration (NHTSA). The NHTSA estimates the cost to society of speed-related crashes to be more than $40 billion each year.

Speeding is a problem not only on freeways, but also on local streets. Many commuters opt to take surface streets, thinking they can more efficiently escape traffic and avoid congestion. A 2002 NHTSA study revealed that 87 percent of speeding-related fatalities occurred on roads that were not interstate highways. Driving 45 miles per hour instead of 35 on a five-mile trip saves less than two minutes.

Traveling over the speed limit can be especially dangerous in bad weather conditions. Speeding was a factor in 53 percent of fatal crashes that occurred when there was snow or slush on the road and in 60 percent of those that happened in icy roads.


Here are things you should remember:

  • Allow yourself enough time to get where you're going, so you don't end up speeding to get to your destination.
  • Check your local traffic report on the Internet before you leave or on your local radio station while you're in your car. That way you'll know where to expect congestion and can take an alternate route if necessary.
  • If you're late, you're late. Don't worry about it. Apologize when you arrive. It's better than speeding and endangering yours and other's lives.
  • Wear your seat belt. It's the law. Click it or ticket!


Footnote for Graph: Estimates for the effect of speed on MPG are based on a study by West, B.H., R.N. McGill, J.W. Hodgson, S.S. Sluder, and D.E. Smith, Development and Verification of Light-Duty Modal Emissions and Fuel Consumption Values for Traffic Models, Oak Ridge National Laboratory, Oak Ridge, Tennessee, March 1999. Graph from: www.fueleconomy.gov/feg/driveHabits.shtml