Actually making 190 proof is not that easy.

I have a very involved reflux still, also a permit to make ethanol, and getting over 186 proof requires 'drying' of the ethanol. The drying process can be using a molecular seive or redistilling in a closed loop system. I distill a 10 gallon mash every run I make and usually I recover about 18-20% of that as alcohol.

I use the full strength stuff to clean my bow hair and the strings of my violins as well.

My stainless reflux still will make 186 proof but after the first 2 qts of a 10 gallon run, the proof drops off quickly.

The next quarts (#3 and 4) are usually in the 175+proof range and the next ones drop from there to around 170 proof for the last quart of good stuff. You would require at least 170 proof to use it in an engine for fuel.

If you use a "pot still" like you see on Moonshiners without the "Thumper Keg" you'd be hard pressed to get better than 140-150 proof but it will have a lot of the flavors of the mash whereas a reflux still will take virtually all the flavor out of the ethanol. Using a T.K. will get you in the 160-170 proof range but it would require a really slow run.

That's just my professional opinion and observations from making the stuff in the real world and not on a TV show. LOL