After I have seen the Chevrolet Volt also as a plug-in hybrid hydrogen fuel cell car
I evaluated again the fuel cells.
They are way to expensive to beat the ICE.
The Chevrolet Volt
15 kWh /100km from the plug
The range extender needs only 13 kWh, because delivering at an other point of the loose chain.
This would be at 50% efficiency fuel cell 0,8 kg
But an hydrogen ICE could have 40%, makes 1 kg hydrogen.
At $15 / kg hydrogen, the fuel cell saves only $3 on 100km.
With an otimistic estimation, fuel cells are down to 1/3 of current price, the fuel cell is about $15.000 more expensive than the ICE.
500.000km to pay with $3/100km the higher price. But since it's a plug-in hybrid, 500.000km outside electric only range.
Even with only 50% of all jouneys in electric mode, 1 million km for the fuel cell to be equal to the ICE.