Ethanol, a wholly renewable alcohol fuel that can be made from corn, grains or biomass, has enjoyed growing favor in recent years. When blended with 15 percent gasoline to create E-85 fuel, it can power internal combustion engines with only modest upgrades in fuel system and engine management software. A variety of current vehicle models are capable of running on any combination of E-85 or gasoline in the same tank. The downside is that ethanol is more costly than gasoline and requires significant federal subsidies to compete at the pump, plus only 1,000 ethanol-fueling stations are found across the country, far too few to support E-85 fueled vehicles as a realistic alternative. Extremely high energy input is currently required to produce the corn that serves as the base for ethanol production. Also, most ethanol-capable vehicles are designated “flex fuel” for the purpose of tax credits or other subsidies, but rarely in fact are operated on ethanol.

The other alcohol fuel, methanol, is typically created from natural gas and thus does not offer the benefit of being a renewable fuel. It is also quite corrosive and requires special fuel lines and other fuel system components. There are very few stations carrying M-85, the motor fuel comprised of 85-percent methanol and 15-percent gasoline, which makes this an impractical fuel alternative.

Two gaseous fuels, LPG and natural gas, are also contenders. A limited number of vehicle models are made to run on these fuels, and they are primarily aimed at fleets because of the premium paid for their costly gaseous storage cylinders and other fuel system components. Plus, like all alternative fuels, fuel availability is an issue. While there are more natural gas stations available than most alternative fuels, this amount is still a relatively small number in the low thousands, compared to the 170,000 gasoline stations found across the country. Propane fueling locations are abundant compared to all other alternative fuels, but almost all are the rudimentary type used for fueling portable LPG tanks for barbecues and other consumer devices, not an attractive or familiar fueling option for drivers. Since LPG is a byproduct of natural gas production, it is in limited supply and subject to price volatility.