TOKYO — Just as critics were wondering about the viability of General Motors’ fuel cell truck partnership with electric heavy-truck startup Nikola, two Asian competitors jumped headlong into the segment.

This month, Hyundai and Toyota each unveiled plans to ramp up development and commercialization of hydrogen-fueled commercial vehicles to be launched from North America to Europe to Asia.

The push into heavy trucking is an uncertain gambit on a nascent technology for all parties. But it could help Hyundai and Toyota achieve scale on the costly fuel cell components and infrastructure necessary for the technology. That, in turn, could speed their rollout of passenger vehicles.

That aggressive foray contrasts with the marketplace murmurings GM heard in September upon announcing a partnership with Nikola Corp. Shortly after word of the GM deal emerged, Nikola founder and CEO Trevor Milton voluntarily stepped down amid public controversy over his optimistic claims about the truck technology.

But Hyundai Motor Co. has stepped up its campaign with deliveries of its new Xcient Fuel Cell, a cabover truck with maximum gross vehicle weight of 19 tons, to customers in Switzerland. Hyundai calls the Xcient the world’s first mass-produced fuel cell electric heavy-duty truck.

Hyundai has also outlined a global road map for rolling out thousands of fuel cell trucks. It wants to make 2,000 for Europe in 2021 and follow that with more trucks for the U.S. and China.

In the U.S., Hyundai hopes to sell 12,000 units of a new 6×4 tractor model by 2030. The company also targets aggregate sales of 27,000 fuel cell trucks in China by then.

Toyota Motor Corp., meanwhile, agreed with its truckmaking subsidiary Hino to jointly develop a fuel cell Class 8 tractor-trailer rig for the North American market based on the Hino XL Series chassis. A demonstration vehicle should arrive in the first half of next year, Toyota said.

Toyota also said it will begin verification trials of a new 25-ton heavy-duty fuel cell truck in Japan in the spring of 2022. A fleet will run predetermined routes, one hauling Asahi beer.

When it comes to hydrogen fuel cell systems, Hyundai and Toyota are arguably the world’s most bullish manufacturers. As rival carmakers cut back on programs, the Asian juggernauts maintain a steady drumbeat of support for the technology and continue to introduce new vehicles.

Hyundai launched the industry’s first mass-produced fuel cell passenger vehicle, the Tucson Fuel Cell, in 2013 and currently offers the Nexo fuel cell crossover.

Toyota introduced its low-volume Mirai fuel cell sedan in 2014, and this year it is expected to start selling a redesigned second-generation model.

The only other automaker currently offering a fuel cell car is Honda, with its equally low-volume Clarity.

For its part, Toyota envisions putting its fuel cell technology into everything from forklifts to buses and trains — and even into a new moon rover it hopes will be launched into space in 2029.

Not all observers are convinced of the technology’s opportunity. Last month, GM received public scrutiny of its proposed tie-up with Nikola, an aspiring maker of fuel cell-powered and battery-powered trucks. GM said it would take an 11 percent stake in Nikola in a $2 billion deal that could put GM’s fuel cell technology into Nikola-built semitrucks.

But a short-seller critic accused Nikola of misleading investors about the company’s technological abilities, casting skepticism not only on GM’s ambitions but on the potential for the fuel cell truck market in general.

Nikola isn’t GM’s only play in the field. Separately, it is partnering with Honda to commercialize the technology. Their joint venture, formed in 2017 as Fuel Cell System Manufacturing, intends to eventually produce fuel cells for commercial vehicles.

But now Hyundai and Toyota are putting the hammer down on commercial trucks. Moving on trucks early will help their passenger car programs, they believe.

“We benefit from both,” said Sae Hoom Kim, senior vice president of Hyundai’s Fuel Cell Center. “It’s not that trucks should go first and passenger cars go later. They should go together.”

For starters, trucking is a more cost-efficient way to spur the setup of an expensive hydrogen fueling infrastructure. A fuel cell charging station can cost upward of $6 million, depending on local regulations. But because trucks run on established routes, over and over, they can guarantee consistent early business for the hydrogen stations. This creates a baked-in network to support passenger cars when they come to market.

Trucks make it possible to sell a lot of hydrogen in one place. According to Mark Freymüller, CEO of Hyundai Hydrogen Mobility, a hydrogen station would need regular visits from 700 passenger vehicles to be a viable investment. But handling just 10 to 15 trucks is enough to float the operation, he said.

“You have your infrastructure setup on a long-term viable business setup,” he said.

Branching into fuel cell trucks also delivers added scale for pricey components, such as fuel cell stacks and high-pressure hydrogen tanks, helping drive down production costs.

The fuel cell system in Hyundai’s trucks, for instance, is based on the same components used in its passenger vehicles — although trucks require more durable fuel cell membranes and catalysts because of the higher number of miles driven. Spreading that technology over bigger volumes helps.

Hyundai expects to build just 11,000 fuel cell passenger vehicles this year. But the addition of 2,000 fuel cell trucks for Europe next year, on Hyundai’s way to supplying the region with 25,000 by 2030, will represent a significant uptick in volume.

Hyundai is also in talks to supply hundreds of fuel cell trucks to a U.S. customer in 2022.

“As we are using the same technology on the trucks, we can benefit from this cost reduction effect,” Kim said.

In coming years, hydrogen trucks will become more competitive with their diesel counterparts thanks to falling costs for fuel cells and rising costs for diesels amid more stringent emissions rules.

Hyundai projects that,because of stricter U.S. carbon dioxide regulations, fuel cells will account for 30 percent of the heavy-truck market in 16 states, including California, by 2030.

Hyundai’s U.S. truck will be based on the sleek, bullet-faced HDC-6 Neptune concept, a hydrogen-powered Class 8 heavy-duty truck it unveiled at last fall’s North American Commercial Vehicle Show.

Its design was inspired by the iconic streamliner trains of the 1930s.

But long term, heavy-duty trucks can only take the technology so far, given limited overall demand in the segment.

True mass scale will only come through fuel cell passenger vehicles. But to get the ball rolling, Hyundai and Toyota are seeking incremental volume from multiple applications.

“That’s why we are using our technology in passenger vehicles, trucks, ships, trains and as backup power,” Hyundai’s Kim said. “We are trying to use this technology everywhere we can.”