How the Michael Franzese gas tax scheme worked? I know they somehow did not pay the goverment, but what was the mechanics behind it? How they managed to do it for so long and how exactly it was being done?

From the horse's mouth.
https://video.nationalgeographic.com/tv/inside-the-american-mob/00000144-1516-dcf1-a954-55df4d960000

Good video, Lou. More detail:
The Russian mob in Brooklyn started the gas scam. Franzese got involved because a Russian mobster involved in the scam needed his protection against a more powerful Russian. In return, Franzese was cut into the scam. Since taxes account for a large percentage of the cost of every gallon of gasoline, it was one of the most profitable schemes in Mob history.

I used to think Franzese was one of the more likable rats...He never bragged about how violent he was or lying about banging Raquel Welch etc..But my opinion changed immediately when I saw that he wouldn't visit his own mother on her deathbed....What kind of bum does something like that ??