How thriftily can you drive? You'll need to ape the hypermilers, writes Paul Markillie, "who disdain the brake, coast into parking spaces and even turn the radio off. And, of course, they are deeply nerdy"...

From INTELLIGENT LIFE magazine, Autumn 2008

Wives have an uncanny knack of knowing what their husbands have been up to. Mine also has a fuel-economy meter. Whenever I borrow her car, I am told to drive more economically and be more light-footed. But I understand all this more than she realises and just to prove it have borrowed her car again--for a journey back in time.

The engine is warmed up, the windows shut (improves aerodynamic flow) and the air-conditioning turned off (it steals power from the engine). My note-taker will be Henry, our smallest boy (less weight). The fuel-economy meter is reset and we're off. Slowly. Our mission is to drive economically, whatever it costs.

To begin with it's mostly downhill, but that advantage will not last because the Hampshire countryside will soon roll up again. Now you might think the best trick downhill is to slip the car into neutral and freewheel. It's not. You need to ape the hypermilers, or nenpimaniacs as the Japanese call them. These folks delight in driving as thriftily as possible; they disdain the brake, coast into parking spaces and even turn the radio off. And, of course, they are deeply nerdy. But to win at this game you need to be. Which is why I had found a helpful person at Toyota to explain how the engine-management system is programmed in my wife's Yaris.

This arcane information is essential because some modern cars have DFC, otherwise known as a deceleration fuel cut, and the Yaris is one of them. It means that if you take your foot off the accelerator at a certain engine speed (above 1,500rpm in the Yaris) the injectors stop supplying fuel to the engine, whereas if the car is in neutral they keep pumping for the engine to tick over. The difference might save only an eggcup of fuel along a stretch of road, but hypermilers care about eggcups of fuel because they eventually add up to gallons. So I leave the car in gear and take my foot off the accelerator. After two miles the meter shows an average of 92mpg (3.07 litres per 100km). Amazing.

Passing through a small town demands more use of the accelerator, but at least the traffic is light. The technique is to keep things as smooth as possible. Feather the throttle, don't brake hard and work through the gears quickly. By the time we have climbed the first hill the average is down to 84mpg. Then it's onto the M3 motorway. I know what to do here: keep the speed at about 50mph and tickle the accelerator. It's called "pulse and glide", a sort of on-off technique carried out very gently to coax the engine along at its most efficient level. Everyone overtakes me, including a car towing a caravan. A lorry driver glares as he roars past, uphill. If there were traffic lights on the M3, we would surely have become victims of road rage.

One more stretch of motorway, a main road and then a turn into the New Forest. By now the average is down to 83mpg, but we can do better. The road is clear. Feathering the throttle and playing the DFC gets the numbers creeping up. Luckily there are no ponies wandering on the road. Straight through the village without touching the brakes, coast up to a junction, turn right and pull up at the entrance sign to the National Motor Museum at Beaulieu to take a photo to prove it: 85.1mpg at an average speed of 37.9mph.

There's a reason for going to Beaulieu. In the fuel crisis of the early 1970s, I was taught to drive ultra-economically in order to compete in a fuel-economy marathon with other journalists. I won the small-car section, wringing 57.4mpg out of a Vauxhall Viva, which usually managed 35. There was no DFC then, but that is about all I can remember about the car. Even a faded press clipping gives little away, apart from my awful hair and even worse fawn suit. The Viva is so unmemorable that Beaulieu does not have one, nor do any of the classic-car enthusiasts attending a show there. But there is a man with a nice drophead E-type Jaguar and we spend a while discussing how he rebuilt it.

Blame the E-type. I reset the meter for the journey home but drive the car to enjoy it. The Yaris is sprightly with its torquey 1.4-litre diesel engine. This time I sprint up the hills and leave the lorries for dust. We pull up at the spot we left from with 60.6mpg on the meter having travelled at an average 42.9mph. It was a much nicer journey, still economical, and even better than a champion fuel-miser with big hair could manage in a Vauxhall Viva.



Smart fortwoSmart fortwo 269cm
60.1 mpg 112g/km. From £6,530. A German cutie to park in tiny places.

Citroen C1 Citroen C1 1.0i 343cm 61.4 mpg 109g/km. From £7,295. Small, cheap and with French flair.

Fiat 500 Fiat 500 1.3 Multijet diesel 355cm 67.3 mpg 110g/km. From £10,900. A great little Italian job to rival the Mini.

Kia cee'dKia cee'd 1.6 CRDi diesel 423cm 62.8 mpg 119g/km. From £12,395. South Korean cars get better all the time.

Toyota Prius T3 Toyota Prius T3 hybrid 445cm 65.7 mpg 104g/km. From £17,932. An even greener plug-in version is coming from Japan. Mpg is combined cycle.

Picture credit: kevindooley (via flickr), Motoring Picture Library

(Paul Markillie is innovation editor of The Economist. In past columns he has written about convertible sales and the world's sexiest brakes.)