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Gas prices are up! Wait, no, they're down. Oh hang on, they're up again! But maybe just on the West Coast. Wait, you can get a free gallon of premium if you buy ten jugs of milk from the Piggly Wiggly! But that's only on alternating Fridays with a membership card...
Until Ford finally gets its stuff together and builds that atomic car they designed in 1958, we're all basically stuck with whatever price the gas station has decided on that particular day (unless you own a Nissan Leaf, in which case you're basically stuck within fifty miles of your house or the "fast charger" at the Nissan dealership, which can get you running again in 30 minutes but costs about half as much as the car itself). If you can manage your mileage, you can at least pick and choose what gas station to top off at, but the advice available online ranges from the obvious (don't hit the gas too hard) to the flaky (wave a magnet over the engine block and pray to Petroleus, god of fuel efficiency). Here are five confirmed facts and five confirmed fictions about boosting your fuel economy.
FACT: Running the air conditioner can hurt your fuel economy.
Personal note: as the owner of a car with a big thirsty engine living in the heart of the oven-hot Sun Belt, I was really, really hoping that it would turn out that running the A/C hasn't had any real impact on fuel efficiency for years and years, and that modern automotive air conditioners ran on fairy dust or unicorn blood or something else than the power produced by the car's engine. Nope! The compressor for the air conditioner has to be turned somehow, and the simplest and most efficient way to do so is having the engine do it. While modern air conditioners use less power to operate, turning them on is still going to give the tachometer a twitch and correspondingly ding your mileage. Much better-and cheaper-to roll down the windows and enjoy the breeze. -
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MYTH: Running the air conditioner will ALWAYS hurt your fuel economy.
On the other hand, if you've got your windows rolled down while you're doing 70 on the highway, you're sort of being an idiot and you're also going to be kicked out of your office carpool. At highway speeds (say, above 50 mph) not only is the engine running in top gear and as efficiently as possible, but the increased drag from your open windows is forcing your car to work harder to maintain speed and more than cancelling out the minimal efficiency boost from not using the A/C. -
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FACT: Fuel-injected cars save gas if you turn them off instead of letting them idle.
While it used to be true that starting the engine of a carburetor-equipped car was one of the most wasteful things you could do with it save setting it on fire, fuel injection and starter motor technology has advanced to the point where if the car is going to be sitting still for more than about a minute it's best to just turn off the engine. In fact, this is one of the reasons hybrid engines are practical today, as they depend on the ability to smoothly start and stop the motor as efficiently as possible. This isn't something you want to do in the middle of traffic, you understand, but if you're waiting outside somebody's house or in a particularly slow and horrible drive-thru line you may want to keep this in mind. -
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MYTH: Fuel-injected cars save gas if you replace the air filter regularly.
Another holdover from the carburetor era, this myth seems pretty sensible on the surface. Less gunk on the air filter means more and cleaner air for the engine, so it must be doing something good, right? As it turns out, the systems controlling and monitoring the fuel injection process are already set up to compensate for a bit of dirt in the filter and the engine can go for much longer than usual without an air filter replacement. Fresh new air filters will give you a mild boost in acceleration (about 10% more torque than with one you've been using a long time) but it's not the sort of efficiency cure-all that your local lube shop would have you believe. -
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FACT: Avoiding suspiciously cheap gas stations will save gas.
All gasoline may be created equal, but by the time it reaches your car all sorts of things may have been done with it. The major franchise gas stations typically add proprietary chemicals and detergents intended to keep your engine clean, leading to a miniscule increase in efficiency that they are nonetheless really desperate to tell you about. Smaller franchises or independently-owned gas stations are under a bit less supervision than the larger chains and so might end up putting more ethanol (or alcohol, or half a case of Natural Light) into the gasoline than may be strictly necessary and drastically harming fuel efficiency.
These places always feature too-good-to-be-true fuel prices some ten cents below the norm, distributed from pumps most stations would have traded in as obsolete years ago. There's been some question about certain grocery-store-based gas stations as well, with Kroger and Wal-Mart coming under suspicion of watering down their fuel, but since these stations are naturally cheaper than regular gas stations they are harder to call out as definitely diluted. -
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MYTH: Buying premium when your car doesn't need it will save gas.
Now generally speaking, higher-octane gas will boost your efficiency a smidgen, but it's not really a smidgen that you're going to be able to notice when you're paying the extra amount per gallon for premium or even mid-grade gas. Premium and mid-grade prices are set based on the idea that if you're driving a car that actually requires the good stuff, you should be able to afford a little extra at the pump. Consumer service agencies and the EPA have run and/or crunched the numbers on filling your car up with higher-grade fuel than necessary and in the end you'll actually be wasting money. -
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FACT: Non-ethanol gas is more efficient than corn-based "gasohol."
One of the reasons why premium fuel really is more efficient than your piddling peasant gasoline is that at no point did corn enter the process. Corn-based ethanol is sort of a bad joke in the biofuels industry, since not only has it been proven to screw up your car's personal fuel efficiency, it's also been shown that the process of raising, harvesting, and processing corn into ethanol uses so much gasoline itself that if corn farmers in the United States weren't massively, absurdly subsidized, corngas would basically cost more than regular gas. Brazil (who has been using biofuel additives since the Seventies) uses sugarcane ethanol, which is considerably more efficient, and China ignored ethanol altogether and instituted a biofuel program centered around ethanol's peppier cousin methanol, but neither of these countries hold important political primaries in states that consist of absolutely nothing but corn, so they're free to do whatever they want.
What can you do about it? Other than expelling Iowa from the United States, not much, but it is possible to use the Internet to find the handful of gas stations that still sell regular-grade 87-octane fuel free from the touch of corn. They'll be expensive, but not as expensive as typical premium gas, and you should see a boost of around four or five MPG. Some gas stations will also have occasional events where they sell midgrade at regular prices and premium at midgrade prices, but if you want to take advantage of that you should be ready for a lot of waiting in line. -
8 of 10MYTH: Fuel additives/special gizmos/voodoo magnets will improve your efficiency.
"If it's too good to be true, it isn't." There are few places that truism applies more than the last five or six pages of a car magazine and the zillions of ads for magic shiny film that makes your license plate impossible to photograph, enchanted sex hormones that will lure women into your Camaro, and always some sort of nifty piece of hardware or fuel pill or completely vague "treatment" for your engine that will lead to unbelievable boosts in performance and efficiency.
Think carefully about this: virtually every car advertisement you can find, even for trucks and sports cars, makes a big deal about how low its mileage is. If GM or Toyota or BMW or hell, even Porsche could get you the sort of efficiency improvement that bolting a funny trumpet-looking thing to your air filter or waving an enchanted thighbone over your engine block claims, don't you think they would have done that at the factory? Or maybe included something in the maintenance manual about which specific prayer rituals you must perform over your fuel tank to ensure top efficiency? -
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FACT: Driving the speed limit can boost efficiency by 15-30%.
It's not widely known or understood, but the nationwide attempt to bring the speed limit down to 55 mph during the Seventies wasn't actually part of the government's plan to arrest and imprison Sammy Hagar as part of its War on Fun intiative. In fact, it was part of an attempt to lower reliance on foreign oil after the massive fuel shocks from the Iranian Revolution. Unfortunately, it didn't really work, as virtually everyone just ignored the new speed limit, but research by the Union of Concerned Scientists (who are always concerned about your well-being) shows that nearly all cars are at their most efficient at around 55 mph, with the only outliers being Corvettes and other sports cars with extremely "tall" gearing (e.g. that the highest gear allows the engine to maintain 55+ speeds with minimal effort). Even dropping your average speed from 70 to 60 mph can increase miles per gallon by around 17%, and if you're living someplace where gas is especially expensive (e.g. California, where at the time of this study gas prices were typically worse than $4/gallon) you could save up to twenty bucks a week. -
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MYTH: Drafting big rigs is a totally sane and practical way to boost highway mileage.
Okay, yes, you do in fact derive a mild aerodynamic benefit from huddling up close in the slipstream of a tractor trailer. Anyone who's watched enough racing of nearly any kind is familiar with this technique (known as "drafting"). But you know what? You ain't no Michael Schumacher, or Dale Earnhardt, or Tommi Makkinen, or anyone else who has put in the thousands of hours of professional driving practice required to be less than a foot away from another multi-ton vehicle traveling at highway speeds. You know all those shreds of tire rubber you see along the side of the highway? If you draft big rigs, you might have a chance to see one of those shreds actually fly free of the tire directly into your windshield. So yeah-maybe try and get a few car lengths between you and the next truck you see. Your non-glass-shard-encrusted face will thank you for it.