does ram air affect economy?

What's an STC? I'm definately NOT an aircraft guy.. That would be my dad and he's into military turbines...lol. However, my first tech school teacher was military in the USAF when piston engines were still in use and his opinion was aircraft fuel is chemically different and while it does carry the octane it is not the same as automotive fuel. I've never, nor would i ever run a car on it for that reason.
I knew about the water injection, and also the Germans and thier NO2, plus you have all the kits from the 70s for water injection too...