Battery power is ahead in the race to become the car technology of the future thanks to the likes of Elon Musk's Tesla, but don't rule out the underdog hydrogen.
That's according to major automakers like BMW and Audi.
They are just two of the firms developing hydrogen fuel-cell passenger vehicles as the industry moves away from fossil fuels to meet climate targets.
Germany itself has bet billions on hydrogen fuel in sectors like steel and chemical.
BMW is hydrogen's biggest supporter among German carmakers, and aims for a mass-market model to be ready in around 2030.
Its rivals are also investing.
Volkswagen's Audi brand said it had put together a team of more than 100 mechanics and engineers who were researching hydrogen fuel cells for the whole VW group.
Hydrogen is also seen as a sure bet by top truckmakers like Daimler and Volvo, who see batteries as too heavy for long-distance commercial vehicles.
For now, though, fuel cell technology is expensive, making the production of mass-market cars a challenge.
The cells - where hydrogen passes through a catalyst to produce electricity - are complex and contain expensive materials.
VW group CEO Herbert Diess has Tweeted that it isn't the solution to climate change.
But Toyota takes a different view.
It already has a fuel cell car on sale, though it remains a niche market.
European general manager Stephan Herbst says both battery electric cars and hydrogen could progress side-by-side.
Herbst is part of the Hydrogen Council business group, which forecasts that hydrogen will power more than 400 million cars by 2050.