Salutations, all. As the title suggests, what prospects exists for a vehicle fueled entirely by atmospheric gas? My grasp of necessary properties and calculations is limited, but a few very crude, likely too simple, theories arise in consideration of a vehicle, namely a consumer automobile, powered by gaseous elements already present in the atmosphere. Ultimately, I know the 'what' but not the 'how'... The vehicle would likely be powered by either oxygen (approx. 20% of atmospheric content) or nitrogen (apx. 78%) for reasons of obvious abundance. Would be powered by system that would directly harvest O2/N from atmosphere, consequently avoiding concerns about BOTH possible explosions (i.e-those caused by high-speed impacts involving O2/N tanks exposed to flame...don't think I need to say more) AND additional (and likely significant) weight that would increase fuel economy and decrease unnecessary size. If powered by oxygen, exhaust would consist of carbon dioxide, much like the very similar process utilized by plants. In turn, this CO2 would be "recycled" by the greenery of the world, reproducing O2 for the mutual benefit of both car and plant. Could be powered by carbon emissions... Obvious concerns involve the O2 engine: rockets have been powered by liquid oxygen...but cooling oxygen to such a ridiculously low temperature under the hood from an atmosphere that's only 20% O2 is gravely challenging. Can someone shed light on possible emissions from nitrogen and/or carbon combustion? Anway, it as just a vague query I had about a rogue, likely already-considered idea. Thoughts?