Not quite as stupid as the meme suggests. But maybe Novum can clarify?
Using Vegetable Oil As Fuel
How exactly do you use vegetable oil as fuel? First, you must have a
diesel engine. The spark
ignition used in a standard gasoline-powered engine would have a very hard time achieving combustion with vegetable oil. The fuel lines and pumps in a
gas engine aren't intended to handle this type of fuel, and many of the sensors used to determine fuel ratios in modern cars simply can't cope well with this variation.
Assuming you have a diesel engine, you could use vegetable oil with no other modifications. However, vegetable oil has
very high viscosity. It's so thick that the engine has a hard time atomizing the fuel completely when it is sprayed into the combustion chamber. The result is unburned fuel that clogs the engine.
Vegetable oil as a fuel? While it certainly is an option for a few engines, we're probably a long way from using last night's grease as the fuel of the future.
auto.howstuffworks.com