On Tuesday, the Marion County Commission voted unanimously to open negotiations with Reliance Petroleum Holdings to power certain county vehicles with CNG. Marion County, which includes the city of Ocala, seeks to buy 100,000 gallons of CNG annually over the next decade to reduce a fuel budget that runs about $3 million a year. The commission scored Reliance higher than two other competitors: Nopetro from Tallahassee and All-N-One Fuel from Orlando. Reliance owns the Diamond Oil convenience stores in Ocala. County officials have proposed converting more than 50 vehicles that are less than four years old within two years of cutting a deal. It’s unclear when the final contract will be brought back for ratification.