Natural Gas Vehicles

What is CNG?
Natural gas used as a transportation fuel is called compressed natural gas (CNG). That's because the gas is compressed to a pressure of about 3,600 pounds per square inch (psi) and stored in a fuel cylinder aboard the vehicle. CNG flows into the engine's combustion chamber and is ignited to create power to drive the vehicle.

The Advantages of Compressed Natural Gas

The Environmentally Clean Advantage

  • Compressed natural gas is the cleanest burning fuel operating today. This means less vehicle maintenance and longer engine life.
  • CNG vehicles produce the fewest emissions of any motor fuel.
  • Dedicated Natural Gas Vehicles (NGV) have little or no emissions during fueling. In gasoline vehicles, fueling emissions account for at least 50% of a vehicle's total hydrocarbon emissions.
  • CNG produces significantly less pollutants than gasoline.
  • Tailpipe emissions from gasoline operated cars release carbon dioxide, which contributes to global warming. This is greatly reduced with natural gas.

The Maintenance Advantage

  • Some fleet operators have reduced maintenance costs by as much as 40% by converting their vehicles to CNG.
  • Intervals between tune-ups for natural gas vehicles are extended 30,000 to 50,000 miles.
  • Intervals between oil changes for natural gas vehicles are dramatically extended--anywhere from 10,000 to 25,000 additional miles depending on how the vehicle is used.
  • Natural gas does not react to metals the way gasoline does, so pipes and mufflers last much longer.

The Performance Advantage

  • Natural gas gives the same mileage as gasoline in a converted vehicle.
  • Dedicated CNG engines are superior in performance to gasoline engines.
  • CNG has an octane rating of 130 and has a slight efficiency advantage over gasoline.
  • Because CNG is already in a gaseous state, NGVs have superior starting and driveability, even under severe hot and cold weather conditions.
  • NGVs experience less knocking and no vapor locking.

The CNG Cost Advantage

  • Natural gas is cheaper per equivalent gallon than gasoline.

The Safety Advantage

  • Surveys indicate that NGVs are as safe or safer than those powered by other fuels. A 1992 AGA survey of more than 8,000 vehicles found that with more than 278 million miles traveled, NGV injury rates per vehicle mile traveled were 34% lower than the rate for gasoline vehicles. There were no fatalities reported--even though these vehicles were involved in over 1,800 collisions.

The Financial Incentive Advantage

  • Most states offer tax credits or grant funding for each vehicle converted to natural gas.
  • A federal tax deduction is also available for the cost of conversion.

You can learn more about natural gas vehicles at:

Loss of Federal Tax Credit Results in Higher CNG Fuel Costs

Beginning Jan. 1, 2012, the price for a gallon of compressed natural gas (CNG) at fueling stations statewide increased. The current price reflects the end of a Federal tax credit of 50 cents per gallon and a new 5-cent per gallon Oklahoma fuel tax, which replaces the previously state-required $100 annual fee for a CNG decal.

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