I bet only people in El Paso in 1978 ever heard about the Oglemobile... a 72 Tbird, with a 429 that Ogle took to Cloudcroft and back on two gallons, about 200 miles.

 

By removing the carb, and doing some mods, he accomplished the 100 mpg with a series of hoses feeding a mixture of gas vapors and air directly into the engine.

Gas in the tank passes through a series of filters, which stretch the energy available in each gallon. The invention also stores excess vapors for later use for up to 45 days. Premium gas is needed, as its higher octane level allows for more vapors to build.

https://www.elpasotimes.com/story/news/local/el-paso/2022/03/18/200-miles-2-gallons-gas-tom-ogle-story-trish-long/7090663001

Well, he never proved it, instead, telling the people that offered a 1000 dollars for him to prove it that it would cost him more than that to reinstall the system. 

If they'd give him the money, he'd prove it worked. Nice scam huh? Just like some people who cheated in Nascar, and made the actual amount of fuel in the vehicle hidden and impossible to discover, he convinced one reporter that he'd made a 100 mpg system, then tried to hook a sucker for a 1000 bucks.