A fleet of 500 hydrogen-powered Toyota Mirai sedans will serve as the official transportation for this month’s Olympic Games in Paris, highlighting the potential of hydrogen fuel technology.

Hydrogen engines, which once conjured images of disasters like the Hindenburg, have progressed significantly. Today’s hydrogen cell engines are considered as safe as their gasoline counterparts, but public perception still needs to catch up.

Recently, Toyota’s Derbyshire, England facility developed a hydrogen-powered pickup truck as a novel approach to reducing carbon emissions. The vehicle, the Toyota Hilux, offers a range of 373 miles and can be refueled quickly at a pump, providing an advantage over electric cars’ battery recharging times.

The hydrogen-powered Hilux operates by mixing hydrogen with oxygen in a fuel cell located at the front of the vehicle, while hydrogen storage tanks are positioned at the back. The design is reminiscent of setups seen in some regions, like the Dominican Republic, where vehicles often use propane tanks as a more economical alternative to gasoline.

But a group of 120 scientists, engineers and academics are calling on the Olympics’ organizers to get rid of the Mirais as the official vehicle of the Games, saying hydrogen-powered cars violate the event’s environmental pledges.

While cars that run on hydrogen — which generates steam to power the engines — emit zero carbon at the tailpipe, more than 95 percent of the world’s hydrogen comes from fossil fuels. That, they say, makes hydrogen-powered cars more polluting than other vehicles.

“We are writing to express our concern that Toyota’s promotion of a hydrogen car is scientifically misaligned with net-zero and will damage the reputation of the 2024 Games,” wrote the authors, who include scientists and engineers from the University of Cambridge, Oxford University and the University of Colorado, CNN reported.