While motor efficiency is 90%, drivetrain is less than that because of gearbox. This motor claims to remove this inefficiency.
Making something that performs well at freeway speeds, yet also is efficient when manuvering round a parking lot is hard.
Most companies just hope you don't care about only getting 5% efficiency round the parking lot, because that isn't a large fraction of your energy budget, even when it's so inefficient.
Motor efficiency aside, a total “energy spent for distance moved” accounting will look bad at such low speeds, just because the car has to power non-motor systems and they use energy at the same rate no matter how fast you’re moving. Peak efficiency in a Tesla is at around 25MPH.
https://x-engineer.org/automotive-engineering/vehicle/electr...
It would be hard to design such a system with a big enough supply of gas to survive leakage for the whole life of the motor though.
(and as an aside, hydrogen detecting sensors is an area of astounding complexity and cool effects which are worthy of an HN post all on their own)