Hey Ben,
Sadly it seems that Bio-diesel is not 'all that' either. The whole process for manufacturing bio-diesel requires more energy than what you get out.
The best you can do in the way of bio-diesel is to recycle it from oil that already exists. Like oil from deep fat fryers. Not really enough chip shops to support the amount of cars in the world though.
Yeah, I saw that film too. Quite an eye opener.