Some people can retrofit to run on any oil including cheap oil resturants want to get rid of.
Seems to me that the government is deliberating obsoleting old cars through this mandate. That’s just wrong.
Gasoline engines will not burn restaurant cooking oil, or any oil, for that matter. Only diesel engines can burn waste oil. Some burn it straight up if it's hot out (I know someone who does this with an old Mercedes 300D). Others add a heater to the fuel tank to lower the viscosity of the cooking oil, and have a secondary tank for diesel fuel that the car starts on and burns until the cooking oil tank is hot. If you want to drive a car on cooking oil, get an old used diesel.
You are confused between a gasoline and a diesel engine.
I believe mythbusters tested this on an old mercedes diesel in one episode. It was impressive to say the least.