You may hear friends say that the faster you go over 55, the much less efficient your vehicle will become.
“Driving at 75 miles per hour takes twice as much gas! Slow down!”
That’s a bit of an exaggeration, but the concept holds true. Every vehicle has a particular spot at which it burns the least amount of gas compared to distance covered. But every vehicle is hugely different.
Every model has a different curb weight, variations in engine and design, internal friction between components, etc. So, the ideal speed – or range of speeds – for mileage varies for every vehicle.
Further, every vehicle has different fuel requirements to begin with. A heavy SUV burns much more than an economy compact. So, exactly how much extra gas you burn will vary from vehicle to vehicle. Still, we can estimate the extra money you’re spending if you speed above the ideal range.
The US Department of Energy estimates that for every 5 mph you increase your speed over 60 mph, you’re paying $0.21 extra per gallon of gas (based on a price of $3 per gallon).
How much does this cost overall? Let’s take a simple example and run the numbers.
We’ll assume that you’re driving a car that gets 25 miles to the gallon, and that your daily commute to work is 25 highway miles. At that rate, at the most efficient 60 mph speed and a market price of $3 per gallon, you’re paying $6 in commuting costs every day.
Start speeding, and the price starts rising. At 65 mph, the price for that commute becomes $6.42. At 70 mph, $6.84. At 75 mph, you’re paying $7.26 to get to and from work every day, without even considering any other driving you do.
Long term, that’s an extra $330 per year just to get you to and from work. And that’s with a reasonably efficient mid-size car. If you’re only getting 20 miles to the gallon, you’ll pay more than $400 in extra fuel costs.
The long and the short is that if you want to save your pennies, it’s best not to speed. However, driving in the slow lane isn’t the only way to curb your fuel costs. Here are a few helpful tips to keep your fuel costs as low as they can be:
- Read Your Owner’s Manual – Find out your vehicle’s most efficient highway speed or range of speeds. Knowing this number is half the battle.
- Get a Gas Rewards Credit Card – Some of the best gas rewards credit cards offer 5% cash back on all gasoline purchases, which will reduce the amount you spend at the pump considerably.
- Stay Slim – Reduce the weight of your vehicle by shedding excess cargo. Depending on the weight of your vehicle, an extra hundred pounds can reduce your mileage by up to two percent. Heavier vehicles will feel the drag a little bit less because they’re already so heavy.
- Use Cruise Control – Set your car’s cruise speed to the most efficient speed and you’ll vary from the most effective speed much less.
- Use Overdrive Gearing - An overdrive gear allows you to use a higher overall gear for high-speed cruising. This will greatly lower your engine’s rev while still allowing a typical highway speed.
- Minimize Idling – When your engine is running and you’re not moving, you’re burning gas without any benefit. How do you solve this problem? Listen to traffic reports whenever possible. If you learn that certain highways are backed up, avoid them. You’ll get to where you’re going sooner and more efficiently. You can also avoid the road during high traffic times.
- Minimize Aggressive Driving – Accelerating and braking both waste energy, and thus, gas. Plus, this can lead to accidents which will certainly increase your auto insurance premiums.
Keep the speed in the sweet spot, and you’ll pay the least to get where you’re going. Drive safe!
Published or updated April 4, 2013.