Cold vapor?
 

I have never heard of it, either... https://www.eagle-research.com/fuelsav/hcoxgy.html
They claim it works, but, is it just another fuel mileage scam?

I vote for scam.

Maybe it's a combination of vaporware and cold-fusion.

I think they used a flux capacitor somewhere.

Another 'vaporizer'.
https://www.fuelsaving.info/atomisation.htm

Ya do the Hokey Pokey and you shuffle all about, that's what it's all about!