Electric cars . . . fueled by gasoline? When you think about electric cars, the phrase "Fill 'er up!" doesn't immediately come to mind -- but early in the next century it might. A government-industry team has demonstrated a gasoline-fueled system that could form the heart of a clean, fuel-efficient electric car. The system consists of a fuel processor that partially oxidizes gasoline to create hydrogen gas, which is then sent to a fuel cell that generates electric power. Members of the partnership include the Department of Energy and Arthur D. Little of Cambridge, Mass. In tests conducted in mid-October, the prototype fuel processor generated hydrogen at a rate sufficient to produce 50 kilowatts of electric power -- enough to run a midsize car, says Robert S. Weber, a senior scientist for the project at Arthur D. Little. Although the laboratory tests used gasoline and ethanol as fuels, the system can also use methanol and natural gas as sources of hydrogen. A car equipped with the system would get about twice the gas mileage of a comparable car with an internal combustion engine, Weber says. Electric cars have faced two vexing problems -- the need for heavy batteries that must be recharged after a few hours' use, and the lack of an infrastructure to support the recharging. One attempt to get around these difficulties has been the development of so-called hybrid electric vehicles, which use a combination of electric and gasoline power. Another approach depends on fuel cells working off stored hydrogen. In May 1996, Daimler-Benz unveiled a prototype minivan that carried tanks of compressed hydrogen gas. In October 1996, Toyota announced that it had developed a hydrogen-absorbing alloy, thereby averting the need for storing large amounts of the gas at ordinary temperatures and pressures. The new system, however, needs neither large batteries nor devices to store hydrogen and would take advantage of the gasoline distribution infrastructure already in place. Fuel cell technology is just one of the initiatives that the California Air Resources Board has encouraged the automobile industry to explore, says spokesman Richard W. Varenchik. The system announced on Oct. 21, although promising, needs to be demonstrated in an automobile, he adds. "We're always looking for efficient, low-emission technologies, but when it gets down to it, we want to look at equipment in the automobile, in real-life conditions."