Car Talk's Guide to Alternative Fuels


Will a flex-fuel vehicle run on dried yak poop? No, it's not that flexible. But it will run on E85 – a fuel that's gradually becoming more available across the country, though it's still mostly in the Midwest. What's the scoop on E85? Will it suddenly liberate us from global warming and the financing of Middle Eastern dictators? Will it mean we'll be able to stop projecting American power anywhere there's an oil well? More important, is a flex-fuel vehicle right for you?

What is a flex-fuel vehicle, anyway?

Flex-fuel vehicles can run on gasoline like every other car, or a mix of gasoline and ethanol. E85 contains 85 percent ethanol and 15 percent gasoline.

Flex-fuel vehicles will not run on compost, Kool-Aid or anything found in Willie Nelson's bus.

Why are there so many flex-fuel vehicles around, even in places where there aren't many pumping stations for E85?

Here's one reason: the federal government gives manufacturers a financial incentive to produce flex-fuel vehicles. By selling flex-fuel vehicles, they earn credits towards their mandatory Corporate Average Fuel Economy (CAFE) requirements. So by making vehicles that accept flex-fuel, they can sell more gas-guzzling, but higher-profit SUVs without incurring penalties.

In fact, many of the flex-fuel vehicles on the road today are gas-guzzling SUVs that almost never see a tankful of E85. And the environmental benefits are merely theoretical if these dual-fuel cars and trucks run mostly on gasoline.

There are, of course, other reasons why flex-fuel vehicles and E85 have gotten some attention -- ethanol isn't imported from the Middle East, it's arguably more environmentally friendly than gasoline, and it's aggressively marketed by special interests like state senators from agricultural states, and the Amalgamated Corn Growers Association.

Isn't ethanol already being used in gasoline?

It is. It's mixed into gas in a ratio of 10 percent ethanol and 90 percent gasoline. This mix is called "E10." In 2011, some 133 billion gallons of gas were consumed in the U.S., and 12.8 billion gallons of that was ethanol (about nine percent of the volume). E10 burns cleaner than pure gasoline, reducing local air pollution, or smog.

And in the summer of 2012, the EPA gave the final go-ahead to E15 for use in 2007 and newer cars. E15 is, to put it mildly, controversial, with automakers, powertrain manufacturers and boating enthusiasts, who have promised the apocalypse in the form of destroyed engines if the new higher-ethanol-content fuel was approved. A study by the Coordinating Research Council said that E15 did damage to two of eight engines it tested on the fuel in 500-hour durability cycles (the equivalent of 100,000 miles of normal wear). Another study showed no damage, but it was sponsored by the Renewable Fuels Association, which, you might guess, has a dog in this fight.

Which cars can use E85?

Right now, there are at least 38 models that can run on E85 -- mostly American-made SUVs and trucks, but also vehicles from Mercedes, Toyota, Nissan and others. You can get a full list, here.

Can you adapt a regular car to run on E85?

Not without a chemistry degree, money to burn and plenty of free time.

The materials in your car's fuel system, including plastics and aluminum, need to be designed to handle ethanol. Some components, such as rubber o-rings and gaskets might wear out more quickly or suffer damage, if exposed to ethanol.

Your car's injectors also need to be changed, along with the vehicle's computer.

The changes are inexpensive when done on a mass production basis at the factory. But we wouldn't recommend you try to retrofit a car for E85 at this time.

How is ethanol made?

Right now, ethanol is made from the same corn that's grown to feed livestock. However, a new form of ethanol, called "cellulosic ethanol" is in the works. It'll allow ethanol to be made more efficiently, and from a much wider variety of plants and biowaste, so ethanol production won't have to displace acreage currently used to grow food.

Will it really help reduce our dependence upon foreign oil?

Yes -- somewhat. And we suppose every bit helps. But, it's hard to imagine E85 being a substitute for all the oil we're currently importing.

In fact, using the entire U.S. corn crop to make ethanol would only replace about 10 percent of our oil needs today.

Corn-based E85 is a drop in the barrel. But, if cellulosic ethanol and other ethanol advances are successful, the reduction in imports could be more significant. And when combined with other substitutes for petroleum, it could be part of an energy-independence solution.

Is there enough ethanol to go around?

There's plenty of ethanol; in fact, an oversupply. Many ethanol plants have been idled because of high production costs (translation: the rising price of corn) and the supply glut.

Is it taking away land that could be used to grow food?

Yes. In 2013, 42 percent of the more than 10-billion-bushel corn harvest in America will go to make ethanol, says the U.S.D.A. In fact, use of corn for ethanol has sparked a spirited “food vs. fuel” controversy. According to the Congressional Budget Office, corn ethanol has contributed to a 15-percent food cost hike, and the U.N. Food and Agriculture Organization reports that the biofuel has sent food prices up worldwide.

Do I save money using E85?

No. In fact, it often ends up costing you more. Here's why. There's less energy in a gallon of E85. A gallon of E85 gets you 27- to 30-percent less mileage than a gallon of old-fashioned gas. So, if you're used to getting 25 miles per gallon on regular gasoline, you'll only get a bit over 18 mpg on a gallon of E85. Even if E85 is 10- to 15-percent cheaper than gasoline, you're still not ahead of the game. As Time reports, “If you get 30 percent worse mileage with E85, then it only makes financial sense to choose E85 if it's 30 percent cheaper than regular gasoline.”

Then why would I want to use E85?

Two reasons: reducing energy dependence and cleaning up the environment. Since ethanol is manufactured within the U.S., it helps reduce -- at least a little -- our dependence on oil.

How much ethanol helps the environment is up for debate. First, it takes a fair bit of old-fashioned crude oil to grow the corn to make the ethanol. (Of course, the same is true of regular gasoline. It takes oil to pump, ship and refine crude oil into gasoline.) Second, you don't get as much energy per gallon of fuel when E85 is compared to regular gas. So even though it's cleaner, you burn more of it to go the same distance.

Finally, while E85 emits fewer nitrous oxide emissions per mile, it does introduce a new category of pollutants, called aceta-aldehydes, which contribute to ozone problems. While most scientists agree that ethanol reduces the overall pollution to the environment, it's not without its own drawbacks.

Any special repair or maintenance concerns?

Unfortunately, for those of us in the auto repair business, there are no special repairs or maintenance concerns that we've seen. In time, we hope to discover at least a few major, boat-payment-sized repairs! The use of E15 gasoline could turn out to be a bonanza for us, especially if even half of what the alarmists say turns out to be right.

Where can I get E85?

It depends – a lot – on where you live. Right now, it's for sale mostly in and around the Midwestern corn-producing states. Not surprisingly, that's where the ethanol plants are – in close proximity to all that corn. There are 160,000 gas stations in the U.S. – and only about 1,275 that sell E85. There are ethanol stations in more than 900 cities and 41 states, but geographically the fuel is heavily concentrated in the middle of America. If you live on one of the coasts, your odds of finding Jimmy Hoffa or a Corvette with a four-cylinder engine might be better. Of course, E85 might become more available, but for now that's the reality.

If you want to see if E85 is available in your neighborhood, try out this handy locator.

How do I know if a flex-fuel car makes sense for me?

If you're shopping for a new car and the model you're looking at is available in a flex-fuel edition, we'd advise you to go for it. It'll be a little more money but if E85 becomes more widely available, you'll be ready to start fueling up with corn.

However, we wouldn't suggest changing your new car plans just to get a vehicle that's E85-ready. Many current flex-fuel vehicles are large SUVs or trucks, which are notorious for their poor fuel economy.

Anything else I should know?

Yes, as a matter of fact. Three items come to mind:

Item 1: On cold mornings, when the temperature is below freezing, a car that's got E85 in the tank will run rough until the engine gets up to operating temperature. E85 won't prevent the car from starting, but it will cause it to stall several times.

Item B: Some fuel additives are not compatible with E85. So, if you're used to tossing in a quart of Dr. Bronner's Peppermint Engine Salve, think twice.

Item III. Some manufacturers recommend against towing a vehicle when you have E85 in the tank (because of the lower energy content). If you're hauling your yacht to the harbor, you'll want to use regular unleaded.