Vehicle Conversion Basics

Photo of a Ford Transit Connect converted to run on compressed natural gas.

A Ford Transit Connect converted to run on compressed natural gas.

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, such as converting a diesel vehicle to run on propane, natural gas, or electricity.

Dedicated, Bi-Fuel, and Dual-Fuel Conversions

Vehicles and engines can be converted to "dedicated" configurations, meaning they operate exclusively on one alternative fuel. They can also be converted to "bi-fuel" configurations that have two separate tanks—one for conventional fuel and another for an alternative fuel. Either fuel can be accessed by flipping a switch. Although EPA regulations refer to bi-fuel configurations as “dual-fuel,” the term dual-fuel typically refers to another type of configuration where two fuels are used for ignition. For example, a heavy-duty natural gas vehicle that uses a small amount of diesel for ignition assistance.

Conversion Systems Installation

When you purchase an alternative fuel light-duty vehicle through a dealership the conversion system is installed by the system manufacturer or by a qualified system retrofitter (QSR). Both have met strict requirements in order to convert OEM vehicles. When converting an in-service vehicle, the work should always be completed by a technician associated with a QSR, also referred to as an upfitter or installer, who is associated with a manufacturer that holds all relevant emissions-related certifications, tampering exemptions, and permissions.

To learn more about code requirements, conversion technologies, and installation practices for propane conversions, the Railroad Commission of Texas has developed a four-part series on converting vehicles to propane. The materials were developed under a Clean Cities American Recovery and Reinvestment Act Project Award and provide technical training on retrofitting, servicing, and fueling propane-powered vehicles.