This page gives a brief description of some current alternative vehicle options. To learn more about each type of vehicle click on its title and you will be linked to the Department of Energy’s Alternative Fuels and Advanced Vehicles Data Center.

Hybrid Electric Vehicle (HEV)

A Hybrid Electric Vehicle is powered by both an internal combustion engine and an electric motor.  The engine is fueled by gasoline or diesel and electricity is generated by regenerative braking and stored in a battery.  The battery supplies the electric motor with the electricity necessary to supplement the internal combustion engine. This approach results in increased fuel efficiency.

Plug-In Hybrid Electric Vehicle (PHEV)

A Plug-In Hybrid Electric Vehicle is powered by an internal combustion engine and an electric motor.  The vehicle utilizes conventional gasoline as well as electrical energy stored in a battery.  A PHEV differs from an HEV in that it can gain electrical energy by plugging into the grid. A PHEV can drive some distance on pure electricity.

FAQ: If I drive an electric vehicle will I just be transferring my pollution from petroleum to coal?

No, commercial electricity production combined with an electric motor uses energy far more efficiently than an internal combustion engine. Electric motors convert 75% of the chemical energy from the batteries to power the wheels – internal combustion engines only convert 14%-26% of the energy stored in gasoline (1). The rest of the energy is lost to engine and driveline inefficiencies or used to power accessories (2). Depending on your electrical grid mix, because of the varying efficiencies and emissions of electricity production, an electric vehicle can reduce between greenhouse gas emissions 19-58% (3) (4).

Flexible Fuel Vehicles

Flexible fuel vehicles (FFVs) are capable of operating on gasoline, E85 (85% ethanol, 15% gasoline), or a mixture of both. Designated Flexible Fuel Vehicles have ethanol compatible components and are set to accommodate the higher oxygen content of E85. E85 should only be used in ethanol-capable FFVs.

Natural Gas Vehicles

Natural gas vehicles (NGVs) are either fueled exclusively with CNG or LNG (dedicated NGVs) or are capable of natural gas and gasoline fueling (bi-fuel NGVs).  In general, dedicated NGVs demonstrate better performance and have lower emissions than bi-fuel vehicles because their engines are optimized to run on natural gas. In addition, the vehicle does not have to carry two types of fuel, thereby increasing cargo capacity and reducing weight.

Diesel Vehicles

Advanced diesel vehicles fueled by ultra-low sulfur diesel are among the most fuel-efficient vehicles available today. These clean-burning new vehicles have put their dirty, smoky reputation behind them. The vast majority of them can also use blends of biodiesel, B20 or sometimes higher, with no modification, making them the easiest type of vehicle to run on alternative fuels.

Propane Vehicles

Today, most propane vehicles are conversions from gasoline vehicles. Dedicated propane vehicles are designed to run only on propane; bi-fuel propane vehicles have two separate fueling systems that enable the vehicle to use either propane or gasoline. Propane vehicle power, acceleration, and cruising speed are similar to those of gasoline-powered vehicles. Lower maintenance costs are a prime reason behind propane’s popularity for use in delivery trucks, taxis, and buses. Propane’s high octane rating (104 to 112 compared with 87 to 92 for gasoline) and low carbon and oil contamination characteristics have resulted in documented engine life of up to two times that of gasoline engines.


A converted vehicle or engine is one modified to use a different fuel or power source than the one for which it was originally designed. In an alternative fuel vehicle (AFV) conversion, a conventional vehicle from an original equipment manufacturer (OEM) is altered to run on an alternative fuel like propane or natural gas. A number of suppliers around the country are approved by the EPA to fit alternative fuel conversions.