Behind the wheel of a super-efficient Shell Eco-marathon car

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Gizmag achieved a fuel efficiency of 403.5 mpg (0.7 l/100 km)(Credit: Jeff Moore)

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Having covered the Shell Eco-marathon so many times over the years and with the teams gearing up for this year's competition, we thought it was about time we tried our hand at driving one of the cars ourselves. Suffice to say, we won't be winning any efficiency awards anytime soon.

The Eco-marathon reputedly dates back to 1939, and a bet between US Shell Oil Company employees about who could travel farthest using the same amount of fuel. The competition officially began in 1985 and now runs annually in Asia, America and Europe, with participation open to full-time high school and university students.

There are two classes in which teams can compete. Prototype class cars are designed to achieve the maximum possible efficiency regardless of passenger comfort, while teams competing in the UrbanConcept class must build cars that are both efficient and practical.

The awards vary depending on the location of the competition in which a team is competing, but in Europe there are on-track categories for cars powered by gasoline, diesel, alternative fuel, compressed natural gas (CNG), battery-electric and hydrogen fuel cells. Off-track awards, meanwhile, cover areas like vehicle design and technical innovation.

Efficiency is, of course, the main focus. The current record from an Eco-marathon car is held by ETH Zürich's Pac-Car II with a gasoline fuel economy equivalence of 5,385 km (3,346 miles) on a single liter of fuel.

The car that Gizmag was driving was, of course, not in that ballpark. It was built in 2007 and is a replica of one that was entered into the Prototype class of the competition by a French team in the early 90s. It is used by Shell as a good example of the cars that are entered, while also being suitable for lugging around to media events like the one we were at.

It is a three-wheeler, with two 20-in wheels at the front and one the rear, and is powered by a 163-cc Honda engine that runs on unleaded gasoline. To keep weight down, it's formed of a honeycomb composite chassis and a removable carbon fiber bodyshell that is lifted onto the chassis once the driver is in place.

Therein begin our problems. I am both heavier and taller than is ideal for driving one of these cars. Any chance of placing well at the Eco-marathon gets smaller with every kilo over the minimum weights of 50 kg (110 lb) for the Prototype class and 70 kg (154 lb) for the UrbanConcept class that a driver is. Competing Eco-marathon drivers who weigh less than their class minimum are ballasted.

Simply getting into the car was a challenge, with my having to lie as flat as possible. By the time the roof-shell had been put on, my feet were stuffed as far into the vehicle's nose as they could be, my knees were pressed against the underside of the shell and my head was pushed to one side so that my safety helmet would fit in.

Once ensconced, the view ahead actually wasn't bad, but this of course will vary from car to car. There was an engine ignition switch down by my right leg, a rudimentary set of handlebars for steering and a throttle, brake levers and an engine kill-switch mounted on the handlebars.

The Shell team on-hand advised that, for maximum efficiency, it was necessary to accelerate hard before killing the engine, and allowing the car to coast for as long as possible. By choosing the optimal places on the course to do this, the number of bursts of acceleration required would be minimized and, in turn, so would the amount of fuel used.

Our circuit, however, was a 1.428-km (0.887-mi) undulating loop outside the Lee Valley Velopark that was used for the London 2012 Olympics. Quite aside from navigating an unfamiliar course and trying to work out the best line, it was also necessary to judge when and for how long to accelerate in order to be able to cut the engine off and coast enough to make it just over the brow of the next hill, after which a downhill gradient could carry the car through the next section.

In years gone by, the Eco-marathon was held on flat courses. Increasingly, though relief is being designed into the courses to give the teams an additional challenge, with those that want to trouble the top of the leader-board having to work out where, how hard and for how long their driver should accelerate.

There was also an example of an UrbanConcept class car on show(Credit: Stu Robarts/Gizmag)

By the last of my three laps, I was able to get round the course with about five bursts of acceleration. My first run ate up 17 ml (0.57 fl oz) of fuel, my second 12 ml (0.41 fl oz) and by my third run I was down to 10 ml (0.34 fl oz), with my track knowledge and feel for the car improving. Across the three runs, I averaged 403.5 mpg (0.7 l/100 km), which shows how efficient even the demo car is. Even that was way behind the 576.4 mpg (0.49 l/100 km) set by a driver from one of the competing teams, though, and it's a long way from getting to Rome and back.

The Shell Eco-marathon competition in Asia ran from March 3 - 6 in Manila, the Philippines, and in the Americas from April 22 - 24 in Detroit. The European competition runs from June 30 to July 3 in London as part of Make the Future London in the Queen Elizabeth Olympic Park.

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