The city of Kingsport says its choice to be green is saving taxpayers' money.
Instead of driving gas powered cars, some of the city's police cruisers are powered by propane.
Police have 13 of them, and are getting 10 more.
Back in 2009, the city got a grant that paid for the conversion of 12 police cruisers to propane.
Not long after that, another grant paid for the propane pump and the conversion of three city trucks.
Over the years, they've continued to add to the fleet.
The city says on average, they're saving about a dollar per gallon. "The number one concern is cost reduction as far as fuel consumption and the environmental impact the city fleet was leaving on the local region," says Steve Hightower, the city's fleet manager.
19 more propane-powered vehicles are on the way and expected to hit the road by October.