Most of the nearly 1,700 bi-fuel cars in the New Jersey state motorpool that can also run on natural gas are often being filled with gasoline, and more than half have never been filled with the cleaner-burning natural gas, according to a state audit reported by Newsday on January 20.The state audit also said another 250 of the vehicles had seen less than 10 gallons of compressed natural gas fuel over their lifetimes. A New Jersey state Treasury spokesman blamed a lack of stations where the vehicles could be filled with natural gas as a reason for reliance on gasoline, the Newsday report said. Over the past seven years, New Jersey has spent $9 million to buy the vehicles, which cost about $5,000 more than regular gasoline-fueled cars. As of 2002, the state had purchased 1,692 of the vehicles. Most of the cars were bought under the Energy Policy Act of 1992 requiring states to make 10 percent of their new vehicle purchases include vehicles powered by non-petroleum-based fuels by 1997, and 75 percent by model-year 2001.The review by the Office of the State Auditor covered September 2000 to December 2002, overlapping the administrations of Gov. James McGreevey and former Gov. Christie Whitman, who signed an executive order in 1999 requiring the state to exceed the federal mandate's provisions.McGreevey administration officials said that last year 10 percent of the vehicles had been powered by natural gas. As of November 2002, 56 percent of the vehicles had never been filled with natural gas, compared with 73 percent in 2000. State Treasury spokesman Tom Vincz told Newsday that the vehicles have been mainly fueled with gasoline because there are only three state-run natural gas filling stations. Twenty-one other such stations in the state are run by utilities and other agencies required to use the cars.