I'm not sure if you're aware that mobile gas vans with their exhaust piped in were used extensively by the Nazis, or whether you'd only heard of Zyklon-B and co

I'm not sure if you're aware that mobile gas vans with their exhaust piped in were used extensively by the Nazis, or whether you'd only heard of Zyklon-B and concentration camp gas chambers. https://en.wikipedia.org/wiki/Gas_van https://en.wikipedia.org/wiki/Gas_van "The gas vans were specifically designed to direct deadly exhaust fumes via metal pipes into the airtight cargo compartments, where the intended victims had been forcibly stuffed to capacity" They were used to kill "Jews, Poles, Romani people, mentally ill people, and prisoners".