http://www.guardian.co.uk/uk_news/story/0,3604,1503407,00.html
"A British bus company is testing a new secret weapon that it hopes will help forward its push to cut its polluting emissions - sheep urine.

Stagecoach has fitted a bus in Winchester with a tank containing the animal waste, which is sprayed into exhaust fumes to reduce emissions of harmful nitrous oxides.

Andrew Dyer, managing director of Stagecoach South, said: "It is a novel way of reducing pollution but we believe it will work. There is nothing to worry about - we won't be asking passengers to leave a sample and we won't be carrying a resident sheep at the back of the bus.""