It’s mostly isopropyl ethanol, which isn’t as toxic as Methanol, but not as nice as grain ethanol in normal booze. Not that felons care.
Wouldn't they be able to use the same ethanol as distilled by the crapload for fuel? That has an additive which makes it unfit for human consumption.
You could make isopropyl ethanol by mixing isopropanol and ethanol. That was tried during Prohibition to denature grain alcohol but it was easily defeated by simple distillation.