The Washington State Department of Transportation


Washington’s state government has a strong commitment to reducing its greenhouse gas (GHG) emissions profile. Naturally, the Department of Transportation vehicle fleet was a primary focus of the state’s emission reduction efforts as the largest fuel consumer in the entire state. While reducing emissions was indeed important, the WSDOT still needed a fuel reliable enough to haul heavy materials, and readily available throughout the state’s nearly 20,000 lane miles of state highway.

“Looking at the gasoline gallon equivalent, propane autogas is cheaper. That’s a really big benefit.”

Georgina Willner

WSDOT Fleet Sustainability Coordinator

A propane autogas truck demonstration eliminated initial concerns about range anxiety and the fuel’s ability to offer tailored and scalable refueling options sold officials on transitioning its fleet. In 2012, 21 of the WSDOT’s sedans, vans, and work trucks near Olympia were converted to propane autogas bi-fuel systems. The number has grown to 69 propane autogas bi-fuel vehicles in the years since, with a goal of continuing to expand conversions of the WSDOT’s light- and medium-duty work trucks and vans.

Equipment Fleet Profile

The Washington State Department of Transportation has converted 69 vehicles of assorted makes and models to run on propane autogas bi-fuel systems.

  • 39 Ford F-Series work trucks
  • 10 Dodge Ram work trucks
  • 8 Chevrolet Silverado work trucks
  • 4 Chevrolet Express vans
  • 3 Ford F-Series service body work trucks
  • 2 Chevrolet Impala sedans
  • 2 Ford Taurus sedans
  • 1 Ford E-150 6-9 passenger van


  • 30% less expensive for propane autogas compared with gasoline.
  • $1.75 saved with propane autogas compared with gasoline.
  • 1 ton of reduced carbon dioxide per vehicle annually.
  • No range anxiety for drivers using bi-fuel systems.
  • Easy training makes technicians comfortable with propane fuel systems quickly.
  • Fast ROI even when gas prices are uncommonly low.

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