The Problem: The usual: cars running on fossil fuels.
The Solution: Japanese researchers developed a race car that runs on cooking oil from tempura — a popular Japanese method of frying fish and vegetables. They entered the car in the famed Paris-to-Dakar rally in 2007 as a way of raising awareness about biofuels, which researches say burns cleaner than fossil fuel and without as many harmful emissions. Tempura oil is particularly well suited to Japan — the food is hugely popular, making the cooking oil readily available.
Eco Craziness 2/5. Entering an experimental car in one of the world's most grueling and dangerous races to prove an environmental point might seem nuts, but driver Ukyo Katayama finished the race 68th out of the field of 109 who finished the arduous course. Many didn't make it the whole way, so perhaps a tempura-powered car is not so crazy after all.