Low-level ethanol blends (10% or less) are approved by manufacturers for use in any automobile in the U.S. There is no noticeable difference in vehicle performance when these blends are used, apart from a slight reduction in vehicle fuel economy because of the lower energy content of ethanol. In general, ethanol can corrode certain materials, and the use of higher-level blends, such as E85, may void conventional vehicles’ warranties. These drawbacks can be overcome by inexpensive modifications at the time of manufacture to produce flexible-fuel vehicles.

All diesel engines can run on 100% biodiesel, though it is typically sold in lower-level blends of 2%, 5%, or 20%. In theory, adding biodiesel should slightly reduce fuel economy, power, and torque. In practice, low-level blends are practically indistinguishable from conventional diesel. Biodiesel also has superior lubricity, which reduces wear and tear on the engine and can increase the life of engine components. Manufacturers are gradually certifying their engines to operate on biodiesel blends. B5 is commonly accepted, and B20 is coming into use. DaimlerChrysler recently approved the use of B20 in Dodge Ram pickup trucks.

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Flexible-fuel vehicles are vehicles that can run on blends of up to 85% ethanol (known as E85) and straight gasoline. Therefore consumers can refill their tanks with gasoline if ethanol is not available. This choice of using either E85 or gasoline introduces a new kind of competition into the fuel market. FFVs are otherwise indistinguishable from their gasoline-only counterparts. Henry Ford’s Model T was an early FFV.

According to U.S. automakers, the additional cost to manufacture an FFV is less than $200. Because automakers receive fuel economy credits for selling FFVs, they have typically sold FFVs for the same price as a conventional vehicle.

In Brazil, more than 80% of all new cars sold – a million cars a year – are FFVs capable of using 100% ethanol, and Volkswagen will no longer sell gasoline-only vehicles there. Ethanol supplies roughly 40% of the country’s non-diesel fuel.

U.S. automakers predict that they will have sold 8 million FFVs by 2008. If they all run on E85, it would reduce U.S. gasoline consumption by 4.5 billion gallons a year. A survey in May 2006 found that two-thirds of U.S. consumers are familiar with FFVs, and more than half are interested in buying one.

Because E85 is not widely available, automakers calibrate FFVs to work equally well on gasoline. If E85 becomes a preferred fuel, however, FFVs could be optimized to take advantage of the high octane content of ethanol – improving performance and fuel economy. The Saab 9-5 Bio-Power, shown at right, delivers 20% more power and 18% more torque when it is running on E85 than when it is running on gasoline, simply because it uses a turbocharger.

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Your car may be an FFV – an estimated 6 million, including sedans, SUVs, pickups, and minivans, are on the road today., These include models from DaimlerChrysler, Ford, GM, Mercedes, and Nissan. If the owner’s manual does not make it clear, you may need to check your vehicle identification number to see if you’re driving an FFV. Some of the specific models being manufactured as FFVs include the Dodge Caravan, the Ford Taurus, and the Chevy Tahoe. Toyota is reported to be planning to introduce FFV models in the U.S.

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E85 refueling stations are listed on the Internet, but their scarcity remains a major obstacle to use of the fuel. Only about 1,000 of the nearly 170,000 gas stations in America sell E85, and most of those stations are located in the Midwest. The number is expected to grow as service station owners take advantage of tax incentives to install the tanks and pumps needed to sell E85. A similar number of filling stations – more than 800 – sell biodiesel. All FFVs can run on regular gasoline when E85 is unavailable. Likewise, all diesel engines can run on traditional diesel fuel if biodiesel is not available. A biofuels pump: B20, E85, E10

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This is not recommended. The parts are not expensive, but it requires taking apart the engine and would void the warranty.

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When it unveiled a prototype flexible-fuel hybrid Escape in 2006, Ford became the first auto manufacturer to build an E85-compatible hybrid as a concept vehicle. Such a car, running on E85, would travel about four times farther on a gallon of gasoline than a standard hybrid – more than 110 miles per gallon. A flexible-fuel Prius, starting with a higher fuel economy, would go nearly 190 miles on a gallon of gasoline. But no such cars are available on the market today.

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