A flexible fuel is a cocktail of ingredients -- literally, given that much of it usually consists of ethanol, the form of alcohol found in hard liquor -- that can run vehicles equipped with internal combustion engines that have been rated to use it. Flex fuels, as they're popularly known, can also be used in engines that haven't been rated for them, but it isn't recommended. Ethanol is also a solvent and if the flex fuel contains more than 10 percent ethanol (designated as E10), it will produce undesirable wear and tear. (By the way, flex fuels also aren't recommended for use as actual cocktails. Gasoline makes a deadly mixer.) On the other hand, if your vehicle is rated for E85 -- check the manual or the sticker inside the fuel door -- it can run on a mixture of 85 percent ethanol and 15 percent gasoline.
Flex fuels aren't new. Model-T Fords could run on ethanol as far back as 1908. Rising fuel prices and diminishing petroleum reserves brought ethanol blends back to attention in the 1970s. Now, there are 10 million flex-fuel vehicles in use in the United States and even more in Brazil, where 90 percent of all internal combustion engine vehicles use flexible fuel.
What's the advantage of flex fuel? For one thing, the reduced petroleum content helps preserve existing stores of fossil fuels. For another, it runs cleaner than pure gasoline, without as many contaminates. And the carbon emissions from the ethanol are no greater than the amount of carbon taken in by the plants from which it was distilled, so it's considered carbon neutral. And in some places (though not all) it's cheaper than regular gasoline.
What are the disadvantages? Flex fuel gets lousy mileage, so that cancels out a lot of that cheapness advantage. And the vegetation that goes into making ethanol could have been used as food, so ethanol production reduces the supply of certain foods (including ones used to feed animals raised for their meat) and increases the price (of some foods) to the consumer.
Still, if you're interested in saving the planet you live on and saving a little money in the process, you might want to give flexible fuel a try. And if you're a motorcyclist, you might want to use it in your motorcycle too. Well, you can, though you just might have to import your bike from Brazil. Let's look at some of the bikes that are available...