Propane Autogas – Conversions and Infrastructure

Propane Autogas Patrol Cars: Analyzing Cost, Benefits

January 2017, Government Fleet - Feature

by Thi Dao - Also by this author

Propane autogas conversions add to vehicle costs — how can a fleet make up this cost to get a return on its investment? Photo courtesy of Polk County Sheriff's Office
Propane autogas conversions add to vehicle costs — how can a fleet make up this cost to get a return on its investment? Photo courtesy of Polk County Sheriff's Office

Fleets across the nation have transitioned their vehicles to propane autogas in an effort to reduce fuel costs, reduce maintenance costs, and go “green.” Some of these conversions include patrol vehicles, making propane-autogas the only alternative fuel adopted by multiple agencies for front-line police work. That said, propane autogas conversions do add to vehicle costs — how can a fleet make up this cost to get a return on its investment (ROI)?

Polk County Sheriff’s Office in Florida, overseen by Sheriff Grady Judd, has 1,400 pieces of equipment, about 600 of which are pursuit vehicles, according to Francis Hart, fleet services administrator. Of its pursuit vehicles — 3.6L and 3.9L Chevrolet Impalas —145 run on propane-autogas. The bi-fuel vehicles have allowed the Sheriff’s Office to reduce fuel costs, Hart said. Even with the currently lower cost of gasoline, fuel savings have been about $0.03 per mile driven. 

Determining ROI

“The biggest misconception is propane costs $3 a gallon. It does if you fill up your barbecue grill. But the actual cost of propane is probably about $0.79 wholesale; for gas, we pay $1.96,” Hart said.

That $0.79 per gallon for propane autogas includes a 37 cent per-gallon rebate from the federal government based on gas gallon equivalent (GGE).

The Sheriff’s Office combines this rebate with State of Florida rebates for converting vehicles to reduce costs even further. The state is offering a 50% rebate of up to $25,000 per vehicle for propane autogas conversions.

Hart said return on investment for the conversion takes about 3.5 years, or half the life of the vehicle. After the first year’s expense it becomes an annual recurring fuel budget savings.

Additionally fleet managers are able to more easily pre-pay for fuel when prices are lower and avoid the impact of the volatile fuel price spikes of gasoline, Hart said. The Sheriff’s Office also prefers propane because it’s a domestic fuel.

For fueling, the Sheriff’s Office uses a state contract. Ferrellgas, the distributor, put in fuel sites at substations so that deputies can fuel conveniently. Hart added that the propane autogas fuel sites are a lot easier to put in than gasoline fueling stations.

Benefits & Expansion

One of the benefits of the dual-fuel vehicles is double the range on converted vehicles. A gasoline vehicle may get 300 miles of range, where a dual-fuel vehicle will get about 600 miles.

“If [deputies are] in an emergency or they have to travel a long distance, they don't have to fuel all the time,” Hart said.

Another benefit Hart sees is less soot and carbon buildup in the engine, and propane has no fuel phase separation issues that ethanol-blended gasoline has.

“Patrol vehicles idle for hours and hours, especially K-9 vehicles. That is the worst thing in the world on engines is to sit in the Florida heat idling for hours, with the air running. Propane burns very clean; you don’t get soot and sludge buildup in the motors burning propane,” he explained.

The Sheriff’s Office plans to convert more units, including transportation vans and trucks, to run on propane autogas.


  1. 1. Sgt. I. McCowan [ January 26, 2017 @ 10:45AM ]

    Propane in a vehicle that has the potential of being shot at with a high-power rifle or being used in a chase at high speed? I have seen propane tanks shot at with a rifle and seen the result, it's devastating. This, on the surface, seem like a terrible idea.

  2. 2. Sam Fox [ February 04, 2017 @ 08:08AM ]

    Propane tanks are twenty times more puncture resistant than gasoline tanks.
    Alliance Autogas has a video that demonstrates what happens when a propane AutoGas tank is shot. Absolutely nothing with pistols rounds and the tank was finally penetrated with a very high caliber rifle. The propane vented from the tank, no explosion. This was also tested on myth busters and again no explosion, just vented the contents of the grill tank. Propane has the narrowest window of flammability of any fuel. Don't believe the Hollywood hype.

  3. 3. Mark Meadows [ February 09, 2017 @ 03:40AM ]

    The safest place around a vehicle in a firefight is getting behind that tank.

  4. 4. Mark Meadows [ February 09, 2017 @ 03:40AM ]

    The safest place during a firefight is behind that tank


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