Toyota has demonstrated this on the Corolla H2 Concept. Their CEO, Akio Toyoda also raced this car to emphasize safety. The engine is not fundamentally different from e regular ICE engine, probably other seals, fuel lines and injectors. A quote from the press release[1]:
The car utilizes the turbocharged inline-3-cylinder engine from the GR Yaris, but with a few alterations to accommodate the hydrogen fuel.
Because the hydrogen is delivered in pressurized gas form, the same kind used in its Mirai FCEVs, Toyota teamed with Denso to develop special fuel injectors that could safely and efficiently introduce the hydrogen—which has a higher ignition temperature than gasoline and eight times the combustion speed—into the combustion chambers.
“Controlling abnormal combustion is the key to hydrogen engines,” said Naoyuki Sakamoto, the Chief Engineer of the project. “The abnormal combustion has the potential to add stress to the engine hardware. Therefore, we developed high-heat parts as well as adjusted the ignition timing and fuel ratio for the Corolla Sport H2 Concept.”
