[Besoeker]

Originally Posted by macgardener

Nice story.

Fish and chip oil fuels newlyweds' road trip - ABC News (Australian Broadcasting Corporation)

Does anyone know why there isn't more of this sort of thing? There must be a huge amount of used cooking oil out there.

Perhaps not as much as you think.
On the basis of a few simple calculations it might fuel about 1% of passenger cars in USA. If you put commercial vehicles into the mix, it would be less than that.
Scale.......