What's the best way to drive to save fuel?

How you drive in traffic makes a huge difference to your fuel consumption

Potential Fuel Saving: up to 40 per cent

[Extremely worthwhile; easy to achieve in practice]

This is where the calm, go-with-flow driver wins big-time, while the alpha male with rabies really is the biggest loser.

We had 12 goes at this, with each one driven in moderately dense arterial roads. That meant 60km/h and 70km/h limits, on roads festooned with traffic lights, with normal daytime, but not peak, traffic densities. 

Half of those 12 runs - each was a total of 20km - were driven aggressively but not illegally. That meant jockeying for position in traffic, getting away smartly hen the lights changed green, and braking rather late for the red lights that inevitably and frequently slowed us to a stop. In other words, the way an annoying, aggressive driver would drive, but without breaking the law.

The other six runs were driven smoothly and gently, more or less keeping up with the traffic and going with the general flow. We accelerated gently (but not painfully so) when the traffic lights went green, and we lifted off early when they went red, coasting to a halt instead of braking heavily. We didn't jockey for position in traffic, but we didn't hold anyone up, either.

Basically, we covered off bothe ends of the 'allowable driving' spectrum in order to best quantify what variation there is in fuel consumption across the range of possible, legal driving styles in traffic. We also measured the time for each trip.

Here’s the rub: From A to B it was absolutely not quicker to drive like a goose. All that posturing for position achieved nothing in terms of travel time. All the runs over 20km were conducted within under two minutes of each other. This is because the sequencing of traffic lights is the great leveller, time-wise. It explains the common experience of having some goose carve you up in traffic, and yet you keep pulling up next to him at most subsequent red lights. (One of the 'smooth' runs was actually the quickest of the 12, but only by about 12 seconds...)

It's a lot more relaxing to drive for peak economy, too. And the general tone of aggression on the road might come down a notch if more people drove economically. Although there's no evidence to support it, road safety would probably improve, too - driving aggressively cuts safety margins in the way smooth driving doesn't, all other things being equal.

Tyre and brake wear increase dramatically if you drive aggressively, too. And with an average set of premium tyres costing about $800, and several hundred more for brake refurbishment, the economic benefits of smooth driving are obvious and significant.

The fuel bill alone for aggressive driving was 40 per cent higher. And therefore, so were the carbon-dioxide emissions.

If these two styles represent opposing ends of a spectrum of driving styles spanning  40 per cent difference in fuel consumption, t's reasonable to assume that, collectively, if people drove a little more conservatively in traffic, we could save (say) 15 per cent right there.

According to Ausstats, Australians drive about 120 billion kilometres annually in capital cities and other urban areas. That's about 60 per cent of our total driving. And 60 per cent of 15 per cent potentially saved by taking it easy when driving in urban areas equals about nine per cent off the nation's annual fuel bill - in other words, 2.7 billion litres less in terms of dependency on foreign oil and 3.8 billion fewer kilograms of annual CO2 emissions. Just by driving more smoothly and less aggressively in traffic.