Ford Motor Co. announced yesterday that it would develop an experimental fuel-cell car powered by a hydrogen-burning internal combustion engine by year’s end. The company, which just opened a hydrogen fueling station at a Michigan research lab, said it is making progress in developing an on-board fuel processor that would generate hydrogen from gasoline, then feed the hydrogen into a fuel cell. Fuel-cell vehicles would be up to 50 percent more efficient than gas-powered cars and up to 90 percent cleaner, producing no carbon dioxide, carbon monoxide, or hydrocarbons. Ford, General Motors, and DaimlerChrysler all expect to be selling fuel-cell cars by 2004. Meanwhile, some companies have begun to power their computer systems with fuel cells to insure a flow of power without interruption and avoid crashes.