Not so - the St Chamond tank and the derivative SPGs were powered by a petrol-electric system.
The Porsche-designed B-Zug artillery tractor was also a petrol-electric system.
Ferdinand Porsche was a proponent of petrol-electric systems for heavy vehicles - the WW2 Porsche Tiger/Ferdinand/Elephant was
powered by a petrol-electric system.
Regards,
Charlie
First I've heard of this, seems like a single example was built. Ahead of its time with electric motors driven by a petrol engine?
There's also the article on Landships: Holt Gas-Electric Tank