A tri-flexible-fuel vehicle has a regular internal combustion engine but can burn gasoline, ethanol, and methanol in any proportion. Most of the modification to the vehicle is in the onboard computer that controls the fuel injectors. This is also known as a GEM vehicle (for gasoline, ethanol, methanol).
To make a regular gas-only car into a GEM car is very simple and uses already-existing technology. But to put a significant number of these cars on our roads will bring about real fuel competition, which will literally change the world. Learn more here.