Photo by Dean HumphreyAmy Zmolik of EnCana explains the advantages of natural gas-powered vehicles at the company’s booth at the EnCana Energy Expo in Rifle at Grafield County Fairgrounds on Wednesday. Zmolik said the Honda Civic in the foreground is built so it can use compressed natural gas, which sells for a a third less than regular gasoline and burns much cleaner, according to EnCana.