Carbon monoxide (CO) is flammable. It is called by many names like "Producer Gas" but is just CO. A gasoline engine needs nominally to be started on gasoline. But will run at around 65% capacity on CO. A fire will produce CO2 until it reaches a high temperature, I read I think 1300F. Not sure but it sounds reasonable. The fuel can be anything that burns well. Firewood is the first choice on the subject, but coal, biomass, pellets(wood), dry grass, hay, dung, ad infinitum, ad nauseum. Basicly anything that will run a steam engine.
There are countless texts and videos on the web. I have a couple, three books on the subject that predate the web as we know it today. The bookseller (time has lost his name) had a number of books on the subject. He is no longer in business but some books can be found at other esoteric booksellers. I am terribly sorry, I'm old and have lost a good portion of my memory. The subject is widely known, CO has been used as a fuel even in recent days.
The trick is to collect the CO once the fire is hot enough, cool it, and send to a carburator. You won't be able to run 120 MPH, more like 40. But you can run. . . Doing a search for "producer Gas Plants" yielded endless pages of links, some useful, some not so, and some just gimmicks.
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