12 Ways You're Killing Your Gas Mileage

Gasoline may be less expensive in the US than in most other places on Earth, but that doesn't make it cheap. Sure, you could cut down on fuel costs by buying one of the most efficient vehicles on the market, but if you're financing a new car just to save money on fuel, you probably didn't pay attention in math class.

The average American driver can save over $150 a year simply by cutting back on fuel usage by 10%. Other than how much you drive, the way you drive can make a big difference. These are just some of the many ways you're killing your gas mileage on a daily basis.

BTW, hybrids and electrics: All of these tips apply generally to being efficient when you drive, so no matter what type of "fuel" your vehicle needs, these will boost your mileage.

Don't tailgate -- it's ultimately bad for mileage.
Flickr/Tammra McCauley

1. Stopping and starting in heavy traffic

If you're part of the typical 9-5 workday, that rush-hour traffic does more than slowly siphon the joy out of your life; it's bad for your wallet. One of the less obvious consequences of your daily commute is that all the extra accelerating and braking is obliterating your mileage.
What to do instead: Granted, not everyone has the luxury, but if you can shift your workday forward or backward an hour, it will help. A lot. You'll also cut down on your stress levels and the amount of money you need to dump into the swear jar every day.

Slowing down for Corners is bad for your fuel mileage
Aaron Miller/Thrillist

2. Slowing down for corners

Fun fact: every time you use your brakes, your car's forward momentum is converted into heat, which then just radiates off into the ambient air.
What to do instead: Pretend you're a (speed limit-abiding) race car driver. Here's a primer on how to do so to save fuel. Be safe about it, but be smart, and you'll have a ton of fun in the process. I guarantee it.

3. Braking hard for a red light

Just as with approaching corners, braking heavily for a light that catches you off guard is bad for your fuel economy... not to mention your safety.
What to do instead: If you look far enough ahead and are properly maintaining your awareness of what's going on around you, you can often anticipate that a light is about to change, especially if it's one you see often enough to know how long it lasts. That gives you the chance to coast for longer.

4. Blasting your air conditioner with the windows down

To be clear, rolling your windows down on the freeway and blasting your AC on max in the middle of summer is nowhere near as bad for your mileage as it was in the 1950s, when that combination could result in a sudden feeling of weightlessness for your fuel needle. At most, you're looking at a very small percentage, but hey, in the quest for more money, every little bit counts.
What to do instead: Pick one or the other, but not both.

Too much junk in your trunk will cost you at the pump
Peter Gudella/Shutterstock

5. Keeping too much junk in your trunk

There are times when having a few bulky items in your trunk is a sensible thing, like carrying kitty litter if you're going out in wintry conditions, or plenty of extra blankets if you're an anachronistic criminal potentially disposing of... things. The rest of the time it's just dead weight, which A) kills your fuel economy and B) upsets the balance of the car, which could become an issue if you have to suddenly change lanes.

6. Tailgating the car in front of you like a big jerk

Everything else being equal, staying close to the car in front of you would result in better fuel efficiency, since you'd be driving in the lead car's wake (i.e., this is why you so often see race cars drafting one another). BUT, out in the real world, the vehicle in front of you tends to change its speed as the driver's attention fluctuates, and the inconsistency of having to speed up and slow down wreaks havoc on your MPG. Not to mention that tailgating is dangerous and a dick move.
What to do instead: Pick a reasonable speed and distance, and set your cruise control; over any length of time, your car will do a vastly better job of maintaining a constant speed than you can, and that's pretty crucial to fuel economy.

Eco modes help save you a TON of fuel
Courtesy of BMW

7. Ignoring your car's engine mode

Most cars today have a couple of different computer settings that affect how they drive. Sport is obviously the most engaging, while your car's variant of "normal" is the default. Both of those will result in more fuel usage than "eco" mode.
What you should do: Eco is the mode that kinda numbs everything about your car, sapping your will to drive in a spirited fashion -- which saves fuel! On many cars, the "eco" mode also reduces your air-conditioning output, raises the temperature allowance for the engine (a hotter engine has less internal friction and is thus more fuel efficient), and generally does result in pretty significant savings.

8. Getting too excited when the light turns green

Most drivers tend to accelerate away from a light much faster than they really need to. The reasons are myriad, ranging from simply having fun, to showing off, to keeping up with the rest of the traffic around you. But these actions have consequences, people, and a negative impact on efficiency.
What to do instead: If your car has a gauge or a light that tells you when you're driving efficiently, try to keep it in the environmentally friendly zone. I dare you. You might get run over by anyone behind you that wants to get to the speed limit in under 15 seconds, but you'll definitely save fuel.

Bonus: If you really want to know by how much your acceleration habits are killing your efficiency, get one of any number of mileage-oriented apps that take throttle data directly from your car.

Auto Start Stop features are for fuel efficiency
Courtesy of BMW

9. Pushing your ASS button

Not that one. The one on your dashboard. With Automatic Start Stop systems becoming ever more prevalent, chances are good your car knows how to shut itself off at a red light and be up and running again by the time you're ready to hit the accelerator. Pushing the ASS button disables the system, which, you know, costs you fuel whenever you're at a light or a drive-thru.
What to do instead: Um... don't press it? Seriously, though, there is a caveat here. While any car with such a system has a more robust starter, using the ASS feature will still wear that starter -- and several other components -- more quickly. Only you can make the call if it's worth it financially, but in terms of fuel, you'll definitely save by leaving the system on.

Properly inflate your tires for better fuel mileage
Flickr/Ronny Kerr

10. Under-inflating your tires

Yeah, yeah, tire maintenance is basically car maintenance 101, but it's something that's oft overlooked when trying to eek out the best gas mileage possible. When your tires are under-inflated, they have more rolling resistance, which means it takes more energy to move them.
What to do instead: Buy an air gauge -- a good one, not one of the $3 specials at the grocery store -- and check at least every couple weeks or whenever the weather changes dramatically. Or, if your car has a built-in tire pressure display, check it daily.

11. Neglecting your maintenance in general

While we're on the subject, if you don't keep up with things like oil changes, you're making your engine work harder to do the same job.
What to do instead: Change your oil whenever it truly needs it.

Roof racks are bad for your mileage

12. Leaving your roof rack on when you're not using it

When it comes to hauling camping gear and all the miscellaneous crap you can't fit inside your car, a roof rack is two thumbs way up. It's also a surefire way to increase aerodynamic drag in a big way, which saps your efficiency at highway speeds.
What to do instead: Unless you're hell-bent on maintaining your "active" image (not that there's anything wrong with that... other than the mileage!), remove your rack when you get home.

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Aaron Miller is the Cars editor for Thrillist, and can be found on Twitter and Facebook. You can probably guess which of these he does willingly, every single time he gets in a car.