Fuel consumption feature
We put the Federal Government's fuel-saver advice to the testWho's fuelling who?
With the odds narrowing on $2 per litre by Christmas, nothing gets middle Australia hot under the collar like petrol prices. It's become a bigger issue even than interest rates. Saving petrol has become a new national obsession.
The key question: how do you make a real difference here? The Federal Government offers consumption-cutting advice in its Green Vehicle Guide. Among the suggestions is: "use air-conditioning sparingly". Right. Tell that to a Brisbane-based sales rep any time in January.
We've tested the commonly-touted fuel-saving techniques, and some are, frankly, a joke. Only two will make any real difference, though one of the less effective ones might save your licence while another might save your life.
THE WHAT AND HOW
We evaluated six apparently plausible (or at least widely-touted) fuel-saving strategies, plus two consequential issues:
CITY AND SUBURBS
- Easy versus aggressive driving
- Peak versus off-peak travel
- Switching engine off when stopped in traffic (a Green Vehicle Guide recommendation)
- We also quantified the impact of a 25 percent reduction in tyre pressures (simulated poor maintenance) and evaluated toll roads versus pre-existing arterial road routes from a cost- and fuel-saving standpoint
HIGHWAY DRIVING
- Cruise control versus driver-operated throttle
- Cruising at 90km/h versus 110km/h on the freeway
- Driving with windows open versus air-conditioning on
HOW WE DID IT
We took one Calais V6 and one chaotic Sydney road system. A balance was struck between our requirement for experimental control and the slings and arrows imposed by the real world. We used the same pieces of road for the same tests, drove the same direction (to negate the impact of a net gain or loss in elevation), at the same times of day and in the same basic traffic density, and as far as possible varied only the condition under the microscope.
The VE Calais V6 boasts the most popular drivetrain in Australia's most popular car, but the main reason we chose it was the trip computer. Its 'fuel used' function asks the engine control computer how much fuel the injectors are squirting - a precisely known quantity. The readout is presented in increments of 10mL, meaning measurement accuracy better than one percent provided each test consumed more than one paltry litre.
Rating:
Potential Fuel Saving: up to 40%
Verdict: Extremely worthwhile; easy to do
Rating:
Economic Benefit: negative
Verdict: Faster if flowing; almost always more costly
Rating:
Potential Fuel Saving: negligible
Verdict: Annoying and pointless, except in absolute gridlock
Rating:
Potential Fuel Saving: up to 5%
Verdict: Essential for safety, moderately useful for consumption
Rating:
Potential Fuel Saving: 52%
Verdict: Extremely worthwhile; difficult to put into practice
Rating:
Potential Fuel Saving: up to 8%
Verdict: Worthwhile ... but only if you're a leadfoot
Rating:
Potential Fuel Saving: up to 9%
Verdict: You're kidding
Rating:
Potential Fuel Saving: up to 4%
Verdict: Ridiculous
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