Toyota isn't ready to give up on internal combustion yet, and it's working on a hydrogen engine. How long has it been in development? Why isn't it popular?

Ferrari’s hydrogen combustion engine is unlike anything we have ever seen Ferrari has filed a patent in the EU and US for an upside-down combustion engine that runs on hydrogen gas.

The hydrogen engine is not without problems of its own, though, and Ford is working to develop solutions to these. For instance, one major problem is the issue of hydrogen storage.

The Southwest Research Institute has released its second phase H2-ICE2 protype hydrogen-fueled truck engine.

A Rotax piston aeroengine, a popular powerplant for light aircraft, has been converted to run on hydrogen by Austria-based Bosch Aviation Technology.

Airbus is slowing ambitions to develop a hydrogen-fueled airliner by the mid-2030s but is expanding nearer-term plans to flight test unducted and ducted sustainable aviation fueled (SAF) engines ...