And now, it's the wacky eco-races

Contraptions built by schools battle hi-tech teams at the Shell Eco-Marathon, says Richard Lofthouse

As soon as I depress it, an engine stutters to life, except that it has a capacity of just 31 cubic centimetres. A centrifugal clutch engages, but I am feathering it rather than dumping it, pottering along gently. Then comes the end of the pit lane, and as the main expressway of the Rockingham Speedway Oval looms into view, I cut the power completely and an eery silence results. Instead of roaring away I am coasting, at a sedate 15 mph.

Welcome to the Shell Eco-Marathon, which invites teams from all over the world to enter wild and wacky machines with the sole intention of achieving very high specific miles to the gallon. Of course it's a sop to the Greens by an oil company, and of course the total bill to Shell is a drop in the ocean - an estimated £400,000, or one quarter of one hundredth of 1 per cent of Shell's £18bn profit last year.

Nonetheless the results are wholesome, and although the event is also tiny relative to Shell's sponsorship of Ferrari in Formula One, the two are not so different after all.

The organiser Norman Koch notes, "Producing the fastest car in the world has a very great deal in common with producing the most fuel-efficient car, in terms of everything from aerodynamics to weight savings to combustion efficiency to issues of friction to thermal efficiency."

He's right in another way. Like F1, the Eco-Marathon has a scrutineering area and a list of rules, including the one that specifies that drivers wear safety goggles, which provokes plenty of mirthful Dastardly and Mutley nostalgia - even for the competitors who don't remember the iconic Eighties cartoon.

None of this changes the fact that an F1 car does 4-6mpg, but that statistic merely highlights the specific achievement of today's world-record tally of 11,195 mpg, held by Japan. Although such a startling figure is partly down to coasting, it is also the result of scientific ingenuity, technological advance and driver talent.

Being 11 (the minimum age allowed in the competition) is the best qualification for driving - but getting the racing line right, avoiding the merest ruffle in the tarmac that could amount to unnecessary friction, and specifically reaching the perfect mean of equilibrium separating momentum from inefficiency - well, that's as difficult as most other forms of motor sport.

As for the ingenuity, it's not all scientific in the strictest sense, and the magic of this event is that it allows for very serious teams to compete alongside entry-level school teams where budget is so restricted that almost anything will do. This year, a total of 51 teams competed, of which approximately 40 were entries from schools.

Take the Warriner School, Oxfordshire. They decided to enter late in the day, and came up with half a racing bike welded to half a go-kart in an unholy alliance of metal bits, driven by a fan attached to Honda G150 four-stroke engine rescued from a skip. Total budget, as evidenced by perished mountain bike tyres and the use of pipette tubing from the school lab to feed fuel, was £5.

The prize for greatest ingenuity, however, goes to Trinity School, Croydon, whose TSR3 resulted from 500 hours of effort and 18 months' preparation. Its chassis was fabricated partly from surplus helicopter floor from a closing factory, and partly from 4mm polycarbonate glazing material, attached to aluminium angle iron. Fourteen-year-old Josh Evans and his science teacher Gareth Evans fashioned roof insulation into a nose cone, covered shrink-wrapped bicycle wheel spokes with a thin plastic film for an aerodynamic advantage and, in a final stroke of genius, sourced a disused javelin to make a long, rakish steering column.

There were, of course, some very serious entries - and most of them were French. Microjoule, one of the entries from the Britanny Institute of Technology, won the eco-marathon through a combination of aerodynamic design, top-flight components and competition experience. The team's choice of a £10,000, wind tunnel-proofed, carbon fibre monocoque shell reduced drag co-efficient to 0.1, one-third that of the most advanced car, while the weight of the entire vehicle is just 39 kg. The bespoke, carbon fibre wheels cost £700 each and are equipped with special bearings and shod with £80 Michelin Radial tyres designed to eliminate rolling resistance with a square profile.

At the heart of the Microjoule is a thermally insulated, bespoke built one cylinder, four stroke, twin-spark engine with a single injector made by French company JPX. It has a displacement of 30 cubic centimeters and a fuel tank of just 30 ml. All that means 8,264mpg at 15mph.Or, as one of the team tells me, the ability "to travel three times around the equator on the same amount of fuel that Concorde needed to reach the end of the runway". In other words, it can travel 10 miles on half a teaspoon of fuel.

The obvious question is "Why aren't we all driving cars that bear some relation to this?" It's a little bit like asking the average Londoner, "Why don't you cycle to work?" It may seem like a good idea, but on closer consideration the problemsinvolved quickly become apparent. One significant issue isthe fact that in an Eco-Marathon you don't have to keep stopping at red lights. And as for passengers, you would be lucky to fit a ferret up your trousers in machines as small as these.

Another important factor is the matter of alternative fuels. The event allows for this with four fuel classes - petrol, diesel, hydrogen and liquefied petroleum gas (LPG) - in the Eco-Marathon, and from next year they are hoping to integrate them. Integration will lead to an overall sense of competition, but providing a level playing field results in extraordinarily complex questions about the advantages and disadvantages of one fuel versus another for the environment, given for instance that hydrogen results from a chemical process requiring another source of energy, which differs from the refining of oil into petrol. But nonetheless, the future lies in alternatives, and their presence is set to make the Eco-Marathon even more interesting in future years.

Shell, in case you hadn't noticed, has rebranded itself as an energy company instead of an oil company. There's much to doubt about this sleight of hand, but Koch, who like most of us is partly an idealist, is confident that the event will expand beyond its current extent of two French events and one British. There will probably be another leg added to Japan, and later this summer there will be a Scottish Eco-Marathon near Aberdeen.

It's a wonderful event even on a blustery, freezing English day where the rain comes down in sheets. One can only hope that the Shell Eco-Marathon expands tenfold and is properly supported by other car makers. Then it would be really coasting.

The Scottish Eco Marathon will be held at the Grampian Transport Museum near Aberdeen from 20-21 August. For more information, visit info@gtm.org.uk.

www.shelleco-marathon.com