I’ll grant you immediately that nitro will boost your effective head pressures (which, if you could VASTLY increase the extraction stroke on a four-stroke engine, would get you a huge improvement in efficiency), but nitro has this problem (well known problem, actually) of stripping the oil off the cylinder walls, leading to early ring scoring on the bore. Not something that Detroit is going to mess with.
Yeah, but I drove my methanol fueled car only a quarter mile each time.