french fry run off in your gas tank?

my friend Matt runs an entire business based on converting old mercedes (think pre 1984) diesels into be able to run on biofuels.  The idea being that by taking the old french fry oil from macdonalds, or any other veggie oil, you can run a car on it and forget about paying for gas forever.  when he first got started in this I thoguth he was crazy, not for the idea-I just had a hard time believing anyone would pay for a converted old mercedes to run on veggie oil.  Like my gut feeling on this years super Bowl- I was completely wrong.  Not only was he getting customers, he actually had a backlog of people waiting for cars!

check out the link below, it gives some of the other things to consider about running your car on biofuels.  As the song says, 'it's not always rainbows and butterflys, it's compromise that moves us along.."  I still think it's a good idea, but it is worth knowing some of the negatives..

http://www.plentymag.com/features/2008/03/the_green_fiend_biofuel.php