Existing fuel tax laws already exist in every state. It's difficult
for ordinary citizens to figure out how to pay the taxes but some have
already been prosecuted for not paying.
"Florida law demands 29 cents per gallon of homemade fuel, but few pay
it, intentionally or because they don't know the rules."
There are also strict laws against making distilling equipment
(required to make ethanol). But that hasn't stopped me from making my
own schnapps and whiskey. The government just wants their cut so they
can pay for hookers.