A college in Sarasota was reported to have worked on making biodiesel. They used oil from fastfood restaurant fryers. The exhaust supposedly smelled like french fries!
I can see it now... "Scented Biodiesel Sold Here!" "choose from french-fries, chicken, or steak" Next thing you know, you'll be able to buy fish scent concentrate, and play tricks on your biodiesel burning friends.