Hypermiling - motoring's black art

17:01, Aug 17 2012

This trial was undertaken in Australia, but we think the challenge can be applied here in New Zealand to make us think more carefully about how we drive and the cars we choose to save fuel.

For a family-sized European SUV, using less than 8 litres of fuel in 100km of driving is a cause to rejoice. Today you get the feeling that won't be nearly good enough.

Volkswagen has challenged us to drive fuel-efficient versions of four of its most popular models over a couple of drive loops it has devised in a competitive challenge to see what sort of economy we can eke from them.

The Touareg SUV is my final car for the day and after keeping a Golf hatch, CC tourer and a Tiguan compact SUV all well south of the 6.0-litre mark, the 2.2-tonne behemoth is the grand final, my personal Waterloo.

At the 18km mark of the 34km loop it's going surprisingly well, with just 4.9L/100km showing on the VW's clock as I turn onto a 3.6km section of undulating, loose dirt. Hitting bitumen again 10 minutes later, 7.1L/100km now glares at me from behind the steering wheel.

That wouldn't be a terrible result, except that the final five kilometres to the finishing line at Mount Stromlo observatory on Canberra's outskirts is all uphill. By the time I hand over the keys at the top I've logged 7.6L/100km and my earlier hard-earned green smugness has well and truly dissipated.

Even though we didn't quite match the Touareg's optimistic 7.4L official combined (city and country driving) fuel use claim, it's still not a bad result given the steep terrain we covered and the VW's weight. And across the four VWs and about 120km of varied driving, I've averaged 5.3L/100km. Most drivers would take that in a heartbeat.

As a newbie to the black art of hypermiling – a sub-set of people who go to extreme and sometimes bizarre degrees to save fuel – the biggest discovery was that the best results were achieved by not trying too hard.

Many techniques were tried by the assembled motoring media in a bid to save fuel. A few attempted the low-speed approach – to the ocassional chagrin of other road users – while others were sure the answer lay in shifting gears at precisely the right time, or anticipating hills and traffic lights. One was sure that nth degrees of consumption were to be saved by warming up cars for longer before setting off.

None were wrong, and to varying degrees all of those techniques will help. Conferring at the end of the day, there was widespread agreement that momentum is king when it comes to driving economically, riding the fat torque wave of each of the four turbo diesel-powered cars to get a flying start at hills and to allow the cars to roll under a feather-light throttle on downhill stretches.

None of it was as taxing as I had imagined, and most elements would be simple to incorporate into your driving style. It can even be turned into an engrossing game – as long as you don't spend too much time studying your trip computer instead of the road ahead.

It helps – a lot – to start with a car that's geared to economy, and in this respect there are an increasing number of cars on the market offering a variety of fuel-saving technologies as well as the interactive feedback to help you understand how to drive more efficiently.

All of the Volkswagen models we drove – the Golf 103TDI Comfortline, the CC 125TDI, Tiguan 103TDI and Touareg V6 TDI – are fitted with VW's Blue Motion technology. That includes a stop-start function that cuts ignition when the car comes to a standstill, brake energy recuperation, a coasting function that decouples the automatic transmission when rolling under zero throttle input, and intelligent thermal management that quickly brings the cars up to their optimal operating temperature.

All come into play during our drive loops, with the stop-start function saving the engine from sipping while stationary at traffic lights on our urban loop, while the coasting function was a favourite on the steep descent of Mount Stromlo that kicked off each drive.

My final fuel figures aren't class-leading, but they're astonishingly consistent. I finished third out of 12 in each of the four loops – not bad for an economy novice.

It all adds up to show that the right car, and the right attitude, will go a long way towards slashing your fuel bill significantly.

-Fairfax Australia