Ding! Ding! That's exactly what I thought! Now, if I only knew how to run my car on cooking fuel...
Buy a used diesel VW or Mercedes. Live in a hot climate and pour vegetable oil straight in the fuel tank. Done.
If you live in a cold climate you have to heat the veggie oil or it will be too thick. That's when you run the car on diesel, heating the veggie with the hot coolant. There are kits available to do this (check http://frybrid.com for one ).