New trike is powered by manure

This is the new Neo trike, built by toilet and urinal manufacturers, Toto. And it runs entirely on excrement. Well, "manure and waste water".

It's the product of three years of research, development and design and is based on a 250cc trike. Alas, the toilet seat's just for show (so no fuelling up on the fly), but it's powered by purified and compressed livestock waste.

A very clever Toto engineer explained: "The waste and household water are converted to methane gas by fermenting, and the methane gas is converted to bio-gas by purifying." Which means there's no waste on board.

The Neo's just arrived home after a month-long drive from the Toto headquarters in Kokura, Tokyo, having clocked up 870 miles. But that doesn't mean it'll be reaching production any time soon - the manufacturer's sticking to urinals for now.

Still, it begs the question - this bike makes your, er, "emissions" fuel, which means they'll probably be taxed. How d'you reckon that'll work, TopGear.commers?