Two days, 370 miles, the odd set back and concentration like nothing else – that was what faced members of the Diesel Car team when they competed in the 2011 MPG Marathon. Sue Baker reports.

They call it black gold. The fuel we put in our cars’ tanks is almost as precious as the metal on a jeweller’s bench. You practically need a mortgage these days to afford a tankful of the stuff, so any trip to a filling station is a wince-inducing, pocket-robbing experience. All of which means that any way of making your black gold a bit more elastic is a very worthwhile exercise.

So here we go again, involving ourselves in the annual two days of self-inflicted masochism that is the MPG Marathon. There is something about this ordeal by fuel gauge, this purgatory of eco-precision, that lures back Diesel Car writers again and again. So there were a whole bunch of us plotting and planning for this year’s event, including old hands John Kendall, Victor Harman, Peter Cracknell, Andrew Andersz and me, as well as Editor Ian Robertson, competing for the first time.

Our vehicles were as varied as our strategies, ranging from a little Suzuki Swift to a chunky Citroën Nemo van, and including the first diesel-electric hybrid to participate in the Marathon’s 11-year history. Mr Editor was in charge of that, but it didn’t go entirely to plan. Our fellow competitors for the event included a pair of Cornish policemen, an ex rally driver, and some eco training specialists who tutor company car drivers in the dark art of stretching mpg. The rest of us were gluttons for punishment, as many of us had competed before, and were lured back by a strange fascination for the intellectual challenge of economy driving.

The route for this year’s event was positively fiendish, devised by a malevolent brain. Yes you, Mr Ross Durkin, event organiser. It looped a 370-miles figure-of-eight through rural Gloucestershire, pivoting around the start/finish at the Cotswold Water Park, ascending the Mendip Hills, finding the only non-flat bits of motorway in that part of England, and incorporating what seemed like at least half of all the roundabouts in the whole of Britain.

Day one was merely difficult, with its endless circumnavigations of tricky, trafficky roundabouts. As any seasoned economy run competitor knows only too painfully well, a busy roundabout is a devilish encumbrance in the flow of eco-driving. It takes fine judgement, a knife-edge nerve and a modicum of good luck to thread your way through without being forced to brake and lose precious momentum. After painstakingly twirling our way through dozens of these obstacles, we Marathoners began to feel like whirling dervishes, rendered in a trance-like state by the gyrations.

The route was positively fiendish, incorporating what seemed like at least half of all the roundabouts in the whole of Britain.

Nevertheless, the first day put most of us in upbeat mood, especially those in the more economical cars and vans whose fuel gauges hadn’t shifted off full yet, despite a brain-numbingly careful 187 miles of eco-obsessive driving. Then day two and another 183 miles brought a sting in the tail. Carefully nurtured mpg figures that had steadily ascended on our dashboard computers started an irrevocable backward slide when faced with another, even more gruesome barrage of hills and awkward junctions, a multiplicity of little villages and another avalanche of ruddy roundabouts. It was Groundhog day, going endlessly round bits of circles.

Everyone competing had slightly different strategies to try and maximise their mpg, and some were frankly perplexing. Hills need a canny plan of attack, using speed built up on downhill stretches to maintain enough momentum on the next uphill slope to ascend without having to resort to lower gears. Odd, then, that some competitors seemed slower on the downhills than on the ascents.

The traditional way of tackling an economy run was to go bare-footed for an economically light touch on the pedals, and to stay in the highest gear possible for as long as possible. But many of today’s cars come equipped with eco aids such as gear change indicators and instantaneous fuel consumption read-outs, and they merit attention as a guide to driving style.

Most of the old rules still apply. To push up your mpg, push down your speed, aim to cruise nearer 50 than 70 on a motorway or dual carriageway, accelerate moderately and develop an allergy for braking. Keep the windows shut and as many electrical items as possible switched off, shed any unnecessary weight in the car, and spend as much time as possible with the engine revs around the 2,000rpm mark.

Most of all, raise your level of forward observation to drive constantly anticipating and planning for what’s ahead. That is a great strategy for doing well in an economy marathon, and comes with a valuable bonus. It is a style of driving that not only raises the car’s mpg, it also lowers the risk of having an accident. Fiendishly safer.