• The Listener
  • North & South
  • Noted
  • RNZ

On the smell of an oily rag

With the next EnergyWise rally about to take place, Matt Nippert looks at the tricks for getting from A to B using as little fuel as possible.

Jeremy Clarkson may scoff at small cars, but even he might learn something from the Energy-Wise rally. Clarkson, the popular host of Top Gear, said last year: "We all know that small cars are good for us. But so is cod liver oil. And jogging. I want to drive around in a Terminator, not the heroine in an EM Forster novel."

The EnergyWise rally, a biennial event designed to test drivers and cars' fuel-efficiency, takes place around the North Island from November 24-27. And even though it's well known that smaller cars use less fuel, all sorts of vehicles - including sport utility vehicles (SUVs) - are taking part.

Stella Stocks, the Automobile Association's general manager of technical services, laughs and agrees that rating SUVs for fuel efficiency is a bit like ranking gossip columnists on their discretion. A Honda Civic hybrid, the most efficient car in the previous incarnation of the rally in 2006, required less than half the fuel needed by the least-efficient, a Ford Territory XR Turbo, but Stocks says the driver's ability matters almost as much as the car's fuel economy.

"The whole drive behind the rally, pardon the pun, is to show people that they can be fuel-efficient by how they drive."

Neil Gyde, along with co-driver Graham Sharp, won the drivers' crown at the last rally, by improving on his car manufacturer's efficiency ratings by 30%. Although some of the steps the pair took were extreme (example: avoiding puddles on the road as the water slightly increases drag on tyres), many of the lessons learnt during the rally can help regular drivers - even Clarkson - save on fuel:

Drive steadily and sensibly

Lewis Hamilton may have won the Formula One drivers' championship with an aggressive approach to accelerating and braking, but Gyde says this is the approach to take only if you want to finish last in the EnergyWise rally. "As soon as you get into the accelerator-brake mode in commuter traffic or in traffic streams on the highway, you begin to consume quite large amounts of fuel. The secret to good driving is planning well ahead and trying to make sure that you're driving on your own terms as much as possible."

Anticipating where you will need to slow down - to avoid braking and then accelerating - as well as coasting down slopes also help. And Gyde, who introduced speed cameras into New Zealand when he worked for the police, is well aware that speeding not only kills but wastes. Travelling at 110km/h uses 13% more fuel than cruising at 100km/h - and will also save you on speeding tickets.

Keep up maintenance

Gyde says regularly maintaining your vehicle will save you money on repairs down the track as well as on fuel. Driving a car with poorly inflated tyres, says Gyde, is "the equivalent of trying to push a barrow-load of concrete with a half-flat front tyre. It takes a lot more energy - any guy on a building site does that once, then goes and finds an air pump." Gyde recommends looking in your car's handbook for the correct tyre pressure, as well as ensuring your wheels are properly aligned. All up, good maintenance can improve fuel efficiency by 20%.

Don't be a drag

The sleeker your vehicle, the less energy required to push it through the air. Removing unused ski and luggage racks helps to reduce drag, as does keeping the windows wound up. Using the air conditioning can add 3-10% to your fuel bill, so leaving it off is the most efficient approach, but there are intangible costs to this sort of fuel-saving.

Gyde, who drove four solid days during the 2006 rally, says: "It does get a bit warm. You certainly wouldn't want to take the family on holiday under those circumstances.

The type of car you drive determines what sort of trade-off you face when deciding to use air conditioning or wind the windows down. According to a recent article in Slate, it is never efficient to use air conditioning in large boxy cars such as SUVs. These vehicles have naturally poor aerodynamics and so the increase in drag from having the windows down is negligible. For smaller cars, however, driving at high speeds with the windows down uses more fuel than maintaining the same speed while using air conditioning. According to Slate: "The rule of thumb is to keep the windows down while on city streets, then resort to air conditioning when you hit the highway."

Turn off the engine

It may seem self-evident, but leaving the engine off uses no fuel. It is worth asking, particularly with short trips, if you really need to use the car at all. Driving from a cold start uses 20% more fuel than when the engine is properly warmed up.

And, if you're stuck in gridlock or waiting kerbside for any period longer than 30 seconds, you'll save more fuel by turning the engine off than allowing it to idle.

Keep your weight down

This advice is good not only for those contemplating extra helpings of Christmas dinner, but also for your car. The heavier your vehicle is, the more energy it requires to accelerate. Rethinking how many bags you need on holiday - as well as emptying the boot of long-forgotten knick-knacks - can improve fuel efficiency by 2% for every 50kg of weight shed.

Don't be stupid

Stocks says her monitoring team has picked up recklessly efficient behaviour during previous EnergyWise rallies. The most common behaviour that fits into this category is the practice of drafting - driving close behind trucks to stay in their slipstream - which reduces drag but carries big risks. "It's not safe. So you wouldn't advocate that's the way that people should drive," she says.

Other tricks competitors have used to reduce drag, such as making wing mirrors useless by folding them in, are also not recommended. But not all madcap schemes are prohibited. Stocks says drivers can minimise their weight to the bare essentials by shedding clothes. "If they want to sit and drive in their underpants - that's fine. Crazy, but fine."