Flüssiggas translates as liquefied gas.
More information:
http://www.tanks-encyclopedia.com/ww...anne-tanks.php
Now I had seen a published photo of a tank with no turret that was powered by a wood burning engine. I later discovered the Germans had converted other vehicles.
https://www.amazon.com/Wartime-Woodb.../dp/0764332406
Another word for the fuel used by wood (or coal) burning vehicles was Gazogene or Gasogene (used by the British and French as well). Thank you, Snautzer.
Usual disclaimer,
Ed