That’s because the rolling resistance of tyres sucks up about 20 per cent of what pours down the bowser hose.
So tyre companies are taking a significant role in the growing search for better fuel economy.
The latest to join in is Korean manufacturer Hankook with their enfren – short for ‘environmentally friendly’, apparently – a new range which incorporates specially bonded silica.
Hankook says independent testing in Europe showed the enfren had a rolling resistance of 8.32, where a conventional tyre had 10.54, meaning a reduction of 21 per cent.
When that 21 per cent is deducted from the 20 per cent of fuel used up by rolling resistance, it means you’re using 5 per cent less fuel overall.
The European results were repeated last week in testing at Eastern Creek outside Sydney, with the enfrens facing off against a set of conventional steel belt radials.
Taking just over four hours on identical Hyundai i30 SLX CRDi hatches, the test resulted in the conventional tyre using 22.13 litres (5.79L/100km) while the enfren used 21.06 litres (5.51L/100km).
We were given the chance to try the enfrens through a series of slaloms, corners sets and brake tests around the track, but weren’t able to compare it to other low rolling resistance tyres at the track.
We ran an informal – and fairly unscientific — comparison with the enfrens on the manual Hyundai diesel hatch against a set of conventional tyres on a Mazda6 manual diesel hatch. This showed that understeer entered earlier with the enfrens, but not by much, and some of the time difference would be attributed to the difference in wheel size: 16” on the Hyundai and slightly wider 17” on the Mazda.
The enfrens also added a couple of metres to the stopping distance at 70km/h, but at no time did they feel unsafe or out of order for what would be normal circumstances.
And the fuel saving makes them worthwhile, according to automotive industry engine consultant John Cadogan, who says they are a cost-effective solution for fuel economy.
“Car companies should jump at the chance for a five per cent solution,” Cadogan says.
“Rolling resistance is an easy to tackle, retro-fit, bolt-on solution with a direct correlation between consumer and environmental benefit."
“The link between fuel and CO2 is absolute, you can’t reduce CO2 by any other way than to reduce fuel consumption.”
Cadogan says that lwo rolling resistance tyres could save a billion litres a year from Australia’s 20 billion annual burn.
“A billion litres is a football-field sized box – that’s a lot of fuel,” he says.
“The environmental benefit is even better, saving two million tonnes of CO2 per year.
“Then there’s energy security – it would be a much happier thing if the Middle East had two-thirds of the world’s reserves of brussel sprouts. But what they have is two-thirds of the world’s reserves of oil.
“And most other areas where it exists are not sending us Christmas cards either.”