For G.M. and Honda, a Fuel-Cell Partnership

Speaking in Manhattan, G.M.’s vice chairman, Stephen Girsky, and the president of American Honda, Tetsuo Iwamura, said that by collaborating on a common design and components, they would lower costs and reduce development time.

They said they would also work with energy suppliers and state and local governments to expand the network of hydrogen refueling stations, a critical element in fostering consumer acceptance of fuel-cell vehicles.

Fuel cells, which combine hydrogen gas stored in the vehicle with oxygen from the atmosphere to generate electricity, offer driving distances and refueling times equivalent to gasoline-powered cars. Though the electricity is produced on board, rather than drawn from a battery pack, the vehicles qualify as zero-emission because the only byproduct is water vapor. Many researchers regard fuel cells as more promising than batteries as an electricity source for vehicles.

Fuel cells also are expected to play an important role in the federal fuel economy regulations set for 2017 to 2025. A section of those rules allows each fuel-cell vehicle to count as 1.75 conventional vehicles in 2020 and 1.5 vehicles in 2021. Such credits enable automakers to somewhat offset the fuel economy of less-efficient vehicles like sport utility vehicles and large trucks.

Additionally, hydrogen fuel-cell vehicles are deemed important for meeting California’s zero-emission vehicle requirements, which are scheduled to be phased in starting in 2018. Under those rules, automakers would need to sell an estimated 1.4 million fuel-cell vehicles, electric vehicles and plug-in hybrids in California by 2025. And because nine other states are expected to follow California’s so-called ZEV law, automakers would need to sell more than a half-million of those vehicles nationwide in 2025.

G.M. and Honda are considered industry leaders in fuel-cell technology, ranking first and second in the total number of related patents filed from 2002 to 2012, according to the Clean Energy Patent Growth Index.

Honda has produced about 100 units of its fuel-cell FCX Clarity model, which is available on a lease-only basis in the United States, Europe and Japan. G.M. fielded a fleet of fuel-cell Chevrolet Equinoxes that accumulated more than three million miles of consumer road testing.

The automakers’ partnership is the latest example in a series. In January, the Ford Motor Company, Renault-Nissan and Daimler formed a joint development alliance aimed at making “affordable, mass-market” fuel-cell vehicles by 2017. BMW and Toyota have a similar arrangement.

Hyundai and Volkswagen also are developing fuel-cell technology independently.