WASHINGTON-The auto and oil industries have begun lobbying Washington for taxpayer help in bankrolling the billions of dollars that will be necessary to get fuel cell cars onto the road.

Depending on which company you ask, General Motors Corp. or the Royal Dutch-Shell Group, it could cost anywhere from $10 billion to $19 billion to build enough hydrogen fueling stations to make fuel cell vehicles a viable option for consumers. These estimates overwhelm the $2 billion that the Bush administration had proposed spending on hydrogen infrastructure over the next 5 years. General Motors and Shell officials stress that their estimates are only a start-and largely guesses.

General Motors figures that $10 billion to $15 billion could build 11,700 new fueling stations. This would be enough so a driver would always be within 2 miles of a hydrogen station in major urban areas and one station every 25 miles along major highways. This would support about 1 million fuel cell vehicles. Shell's $19 billion estimate would reconfigure about 44,000 existing gas stations-one-quarter of the U.S. total-to dispense hydrogen, too.

Company executives claim that they aren't looking for subsidies yet. But they made it clear that they think Washington will have to come up with tax breaks or other incentives to make the companies comfortable investing real money toward a "hydrogen economy."

"There'll be a point in time-maybe it's a year or two away-when [infrastructure funding] decisions will be more important than the technology," says Byron McCormick, executive director of fuel cell activities at General Motors.