DETROIT - Hydrogen fuel cell cars could one day challenge electric cars in the race for pollution-free roads - but only if more stations are built to fuel them.

Honda, Toyota and Hyundai have leased a few hundred fuel cell vehicles over the past three years, and expect to lease well over 1,000 this year. But for now, those leases are limited to California, which is home to most of the 34 public hydrogen fueling stations in the US

Undaunted, automakers are investing heavily in the technology. General Motors recently supplied the US Army with a fuel cell pickup, and GM and Honda are collaborating on a fuel cell system due out by 2020.