The device attached to this 1942 DeSoto is a wood gasifier -
or producer gas generator.  Its purpose was to provide a practical substitute for increasingly scarce gasoline during World War II.  More than one million non-military vehicles were converted to run on producer gas worldwide during the war and approximately half of them were in Germany.  Wood chips or charcoal were heated inside a sealed, oxygen-restricted metal container in a process called gasification or pyrolysis.  This thermal breakdown produced a flammable mix of carbon monoxide, hydrogen, and methane that was cooled, filtered, and fed directly into the engine's internal combustion system.  While it kept vehicles moving during severe fuel shortages, wood gas had about one-eighth the energy density of gasoline, cutting engine power by roughly 30% to 50% and requiring frequent refueling of the firebox.
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