Five Facts and Five Myths About Saving Gas

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 air conditioner.

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 other than 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, 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.

Another holdover from the carburetor era, this myth seems 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, but it’s not the sort of efficiency cure-all that your local lube shop would have you believe.

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, and so might end up putting more ethanol into the gasoline than necessary, drastically harming fuel efficiency.

These places sell fuel at too-good-to-be-true prices, distributed from pumps most stations would have traded in as obsolete years ago. 

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.

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, corn gas would basically cost more than regular gas. Brazil (who has been using biofuel additives since the 1970s) 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.

“If it sounds too good to be true, it probably is.” There are few places this 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 some piece of hardware or fuel pill or completely vague “treatment” for your engine that will lead to unbelievable boosts in performance and efficiency.

If GM or Toyota or BMW or even Porsche could get you the sort of efficiency improvement you could supposedly achieve by bolting a funny, trumpet-looking thing to your air filter or waving an enchanted thighbone over your engine block, don’t you think they would have done that at the factory?

It’s not widely known or understood, but the nationwide attempt to bring the speed limit down to 55 mph during the '70s 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 similar sports cars. Even dropping your average speed from 70 to 60 mph can increase miles per gallon by around 17 percent, and if you’re living someplace where gas is especially expensive, you could save up to $20 per week.