TREE POWER: Engineers Babak Parviz and Brian Otis demonstrate with students how a device can be plugged into a tree for power. (Photo: University of Washington)

A racing car built partly from vegetables and powered by chocolate is to make its track debut next month.

The Worldfirst - described as the greenest car of its kind - is expected to reach a top speed of 135mph when it hits the track at Brands Hatch.

The technical director at German biomass company BMP Biomasse Projekt, saw a business opportunity in solving the breweries’ grain waste headache. He reasoned that the leftover grain could be used to create steam and biogas, which would provide energy for the breweries, cheapening their energy costs as well as their costs of transporting grain to farms.