Everyone is wishing now that the evil oil companies had kept at least one copy of the 100 mpg plans. /Sarcasm with a capital S
A while back when gas went into the high four dollar range there were some inventive folks who came up with a modification. They pre-heated the fuel so it became a gas before entering the carb. It increased their gas mileage. I don’t know how much but it seemed like a fifteen fold increase.