does ram air affect economy?

"boost will raise vacuum" WTF?

Read again, cooler intake charge will raise vacuum..... WTF!

do you understand the difference between negative and positive pressure

More than you ever will..... thinking in terms of manifold pressure/mixture/EGT's in aircraft. (Same deal)

Colder air is denser, so a given volume of air at a colder temp will use more fuel to maintain a/f.

LOL, well, no, it may need a bigger jet, but the fuel needs will be the same power produced.

Also, think, a cooler air charge can run leaner. (In economy circumstances) Even more if the fuel is HOT and the intake charge s cool.

"Colder air makes mpgs better" WTF?

Yes sir.... Sorry it doesn't make sense to you......So maybe you should do some research, forget automotive, try piston aircraft engines, and all will be clear.