All city-owned vehicles, including dump trucks and garbage trucks, in Chattanooga, Tenn. are now run on biodiesel fuel, the Associated Press reports. City officials say they made the switch to help preserve the environment and to save nearly $50,000 a year, since biodiesel is 25 to 50 cents cheaper per gallon than diesel fuel. During the trial period, officials say they first used B-5 fuel (five percent vegetable or animal oil and 95 percent petroleum) in a few vehicles. As it proved reliable, officials moved to B-20. According to theAP, Kiesche says there was early concern about wear on the truck engines, but they've held up as well or better than expected.