What propane fuel is

Propane is a three-carbon gas (C3H8). It is stored under pressure inside a tank as a colorless, odorless liquid; as the pressure is released, the liquid turns into a gas that is used in combustion. An odorant, ethyl mercaptan, is added so leaks can be detected.

Propane is produced as a byproduct of natural gas processing and crude oil refining. It is the world's third most common transportation fuel, behind gasoline and diesel, and is considered an alternative fuel under the Energy Policy Act of 1992. Propane used in vehicles is specified as HD-5 propane, which must be at least 90% propane.

According to the Propane Education & Research Council, cited by the AFDC, there are nearly 60,000 on-road propane vehicles with certified fuel systems in the United States. Many are fleet vehicles such as school buses, shuttles and police vehicles.

From the AFDC Propane Fuel Basics and Propane Vehicles pages, read November 8, 2026.

How a propane vehicle works

Propane vehicles operate much like gasoline vehicles with spark-ignited internal combustion engines. Propane is stored as a liquid in a relatively low-pressure tank, usually at the rear of the vehicle. There are two types of propane fuel-injection systems:

Vapor injection. Liquid propane travels along a fuel line into the engine compartment, where a regulator or vaporizer converts it to a vapor.

Liquid injection. The propane does not vaporize until it has left the fuel injector, which allows more precise control of fuel delivery and results in improved engine performance and efficiency.

The AFDC says a propane vehicle's power, acceleration and cruising speed are similar to those of conventionally fueled vehicles.

From the AFDC pages How Do Propane Vehicles Work? and Propane Vehicles, read November 8, 2026.

Key parts of a propane vehicle

The AFDC lists these key components of a propane vehicle, among others:

• Fuel tank (propane): stores propane on board as a liquid until the engine needs it, usually at the rear of the vehicle.
• Fuel filler: the receptacle a fuel dispenser nozzle attaches to.
• Overfill protection device: shuts off the flow of fuel into the tank once it reaches 80% of capacity.
• Pressure relief valve: opens and vents fuel from the tank if the pressure goes above a preset level.
• Tank valve: a manual valve that stops fuel from entering or leaving the tank.
• Fuel filter: traps contaminants so they do not clog parts such as the fuel injectors.
• Electronic control module (ECM): controls the fuel mixture, ignition timing and emissions system, and detects problems.
• Spark-ignited engine: fuel is combined with air, and the air/fuel mixture is ignited by the spark from a spark plug.

From the AFDC page How Do Propane Vehicles Work?, read November 8, 2026. The AFDC also lists the battery, exhaust system, float assembly, fuel injection system, fuel line, pressure gauge and transmission.

Dedicated vs. bi-fuel

There are two types of propane vehicles:

• Dedicated: designed to run only on propane.
• Bi-fuel: two separate fueling systems, so the vehicle can run on either propane or gasoline. Having either fuel available typically gives a bi-fuel vehicle a greater range than a dedicated propane or gasoline vehicle.

Extra storage tanks can increase range, but the tank size and added weight affect payload capacity. From the AFDC Propane Vehicles page, read November 8, 2026.

Propane vs. gasoline

Propane has a higher octane rating than gasoline but less energy per gallon:

From the AFDC Propane Vehicles and Propane Fuel Basics pages, read November 8, 2026. The higher octane rating lets propane be used with higher engine compression ratios and makes it more resistant to engine knock. The AFDC gives the on-board tank pressure as about 150 psi (about twice the pressure of an inflated truck tire); fueleconomy.gov says propane fuel tanks are rated to 300 psi.

Conversions and prep-ready engines

Propane vehicles are available from original equipment manufacturers or through a conversion. Fueleconomy.gov says a few light-duty vehicles, mostly larger trucks and vans, can be ordered from a dealer with a prep-ready engine package and converted to use propane, and consumers can also convert in-use conventional vehicles.

Fueleconomy.gov says a conversion installs either a separate fuel system (for a vehicle that will use both a conventional fuel and propane) or a replacement fuel system (for propane-only operation). The AFDC says conversion systems must be certified as compliant with U.S. EPA regulations (and/or California Air Resources Board rules), and a qualified system retrofitter (QSR) should perform the installation. The AFDC names Ford's Qualified Vehicle Modifier program as an example of a QSR.

For medium-duty vehicles, prep-ready engines are designed to handle the higher temperature and lower lubricity of propane, according to the AFDC.

From the AFDC Propane Vehicle Conversions and Propane Benefits and Considerations pages and fueleconomy.gov's Propane (LPG) page, read November 8, 2026. EPA keeps a list of compliant alternative fuel conversion systems.

Fueling a propane vehicle

Stations. Fueleconomy.gov says about 990 public fueling stations sell LPG in the U.S. The AFDC Alternative Fueling Station Locator lists public and private propane stations and can prioritize stations with vehicle-specific fueling capabilities.

Primary and secondary stations. Primary stations have dedicated vehicle services. Secondary stations mostly serve the propane tank and bottle market, such as grill canisters and mowers; they can fuel propane vehicles but have limited vehicle-specific fueling capabilities.

Connectors. NFPA Code 58 (beginning with the 2017 version) requires the quick-release Type K15 connector on all new propane vehicles as of January 1, 2020. It allows one-handed fueling and does not require the gloves and face shield needed for the older ACME connector. An adapter lets the Type K15 nozzle fuel vehicles with the ACME connector.

Fill limit. The tank's overfill protection device shuts off the flow of fuel after the tank reaches 80% of capacity.

Station count from fueleconomy.gov's Propane (LPG) page; station types from the AFDC Propane Benefits and Considerations and Propane Fueling Stations pages; connectors from the AFDC Propane Fuel Basics and Propane Fueling Stations pages; fill limit from How Do Propane Vehicles Work?, read November 8, 2026.

Benefits and drawbacks

Benefits

• 86% of the propane used in the U.S. comes from domestic sources (fueleconomy.gov).
• Usually cheaper than gasoline (fueleconomy.gov), and propane at primary fueling sites typically costs less per gallon than gasoline (AFDC).
• Potential for lower maintenance costs, and propane's low-carbon, low oil-contamination characteristics may result in longer engine life (AFDC).
• Potentially lower toxic, carbon monoxide and non-methane hydrocarbon emissions (fueleconomy.gov).
• Cold-start problems can often be reduced, because the propane and air mixture is completely gaseous when it enters the combustion chamber (AFDC).

Drawbacks: Limited vehicle availability and a limited number of fueling stations (fueleconomy.gov). Fewer miles on a tank of fuel (fueleconomy.gov). Converting a vehicle to use propane is expensive (fueleconomy.gov), and propane vehicles can cost several thousand dollars more than comparable gasoline vehicles (AFDC). From fueleconomy.gov's Propane (LPG) page and the AFDC Propane Vehicles and Propane Benefits and Considerations pages, read November 8, 2026.

Maintenance and service at Michigan City Ford

The Works® at Michigan City Ford includes a synthetic blend oil change, tire rotation and pressure check, brake inspection, Multi-Point Inspection, fluid top-off, battery test, and a filter, belts and hoses check. Check your owner's manual for the fuel your vehicle takes, or ask our service team.

Schedule service online and see our service specials first. Michigan City Ford is at 3930 Franklin St. in Michigan City. Get directions.

Michigan City Ford service hours

From Michigan City Ford's website, November 8, 2026. Holiday hours can differ.