I’ll go down to the station and fill up then, woops.
The simple fact is that we cannot produce enough vegetable oil to make any impact on the fuel market. It is very similar to the current ethanol situation.
There is some real potential for biofuel in the future but it relies on currently unrealized, more efficient technology, both in fuel production and vehicle efficiency.
Currently, biodiesel is a good hobby for the self sufficient. However, if you could divert enough vegetable oil to the fuel market to add a couple percent of our fuel needs, you would send the market into a speculation nightmare.