There are close to 17.4 million Flexible Fuel Vehicles on US roads.
All gasoline vehicles in use in the U.S. today can accept gasoline blended with up to 10 percent ethanol (sometimes called gasohol). Flexible Fuel Vehicles (VVFs) are cars and trucks that can use any level of ethanol up to 85 percent. They're built with special fuel system components designed to be compatible with higher ethanol concentrations.
Flexible fuel vehicles are identical to gasoline-only models except for a few engine and fuel system modifications.
FFVs experience no loss in performance when operating on E85, and some generate more torque and horsepower than when operating on gasoline. However, since ethanol contains less energy per volume than gasoline, FFVs typically get about 15%–30% fewer miles per gallon when fuelled with E85.
The E85 component modifications also changes from company to company. For example in Vortec 5.3L Gen IV V-8 engines used in General Motor cars, only the fuel rail and fuel injectors are different between E85 versions and non-E85 version.
A new virtual fuel sensor reduces the cost and complexity of adding E85 capability to the fuel system. The ECM samples the exhaust at the oxygen sensor, and an algorithm determines whether E85 is used, as well as its mixture percentage with gasoline. It’s a much simpler, less costly system than previous systems that relied on fuel composition sensors. In fact, the entire system on the engine is simple: only the fuel rail and fuel injectors are different between E85 versions and non-E85 versions.
Technically, a non-flex fuel model can be modified to run on E85, but it is not cost-effective since several parts of the FFV fuel delivery system needs to be modified to be made E85 fuel compatible.
The significant difference is the fuel sensor which detects the ethanol-to-gasoline ratio. A number of other parts on the FFV’s fuel delivery system are modified to be E85 compatible. The fuel tank, the fuel lines, fuel injectors, computer system and anti-siphon device have been slightly modified. Alcohol fuels can be more corrosive to certain metals than gasoline; therefore, fuel system parts have been upgraded for high level ethanol use.
There are EPA certified kits for converting conventional gasoline-fueled vehicles to run on E85 fuel.
Pure ethanol (100% ethanol or E100) could theoretically be used to power flexible fuel vehicles (FFV) however not used for the following stated reasons.
Ethanol is bad for cold-starting, because it doesn’t burn as quickly as gasoline. (It has a higher octane, if you’re interested.) Pure ethanol would be useless as fuel in the winter months.
There are no passenger cars designed to take E100 (but some racing cars are) so it could damage your car engine. Even Flexible-Fuel vehicles (FFVs) – which can run on petrol or ethanol – can only take up to E85.
We have many people using E98 and E100 in their converted vehicles. Every car is different so you will need to play mad scientist and experiment with the water content. Too much water displaces the oxygen in the cylinder resulting in an anti-dentonant. Not enough water then results in wasting fuel. The E85 Conversion kit manufactured by Fuel Flex International FFI was featured in the movie PUMP.
Flexible fuel vehicles have an internal combustion engine capable of operating on gasoline, E85 (a gasoline-ethanol blend containing 51% to 83% ethanol), or a mixture of the two. FFVs' which are considered alternative fuel vehicles (AFVs) have one fueling system, which is made up of ethanol-compatible components and a powertrain controller calibrated to accommodate the higher oxygen content of E85. The fuel system components are described here.
North American and European flex-fuel vehicles are optimized to run on E85, a blend of 85% anhydrous ethanol fuel with 15% gasoline to reduce ethanol emissions at low temperatures and to avoid cold starting problems during cold weather. There is a winter blend of E70 in the U.S. from November until March. Technically, a non-flex fuel model can be modified to run on E85, but it is not cost-effective.