Does My Car Have a Drinking Problem?


Very few - if any - cars deliver same fuel consumption claimed in the specifications, when you drive them 'out there' on the road.

Fuel consumption is an increasingly important factor in car buying decisions these days. When the car doesn't measure up as advertised, many owners approach the dealer, get fobbed off, get angry and threaten legal action.

This video explains how and why the car is probably not defective in this situation - hopefully before you hire a lawyer...

A comprehensive story on official fuel consumption is here >>


Does your car have a drinking problem? Let’s find out.

The glossy brochures always paint a rosy picture about fuel economy but then, out on the road, the car always seems to drink excessively. How, exactly, does that work?

But the consumption seems excessive. It’s not delivering as advertised. That’s a fail. In this situation you go back to the dealer.

 Maybe it gets ugly. You get fobbed off. Your intelligence gets insulted. You get angry. It’s understandable. It seems like the car is defective, and nobody cares, except of course you.

 The good news is: Your car is probably not defective. Let’s take a look at how those official fuel numbers are determined.

Official fuel consumption is part of the Australian Design Rules, or ADRs. These are the official compliance standards for new cars in Australia. They cover just about everything. The fuel economy standard is called ADR 81/02.

Car companies do those fuel tests in government-audited independent laboratories. They aren’t driven on roads; they’re connected to machines called dynamometers. Every version of every new model gets tested separately. Two highly standardized tests are conducted – the Urban and Extra-urban tests.

Combined, both tests take 20 minutes. In the 13-minute Urban test, the car averages 19km/h. It spends a total of six minutes stopped. It actually stops 12 times during that test and peaks at 50km/h, four times. In the seven-minute Extra-urban test, meant to simulate highway driving, the average speed is just 63km/h and the maximum is 120. A total of 40 seconds is spent stopped.

The tests cannot be faked. So nobody’s cooking the books. They’re repeatable, standardized and tightly controlled. But they’re about as unlike actual driving as you can get.

On one hand, they’re quite good for comparing different cars you might be thinking about buying. In other words, good for relative comparisons. The manual versus the auto. The diesel versus the petrol. The Mazda3 versus the Hyundai i30. The tests are actually pretty good for that kind of comparative shopping.

Unfortunately they’re also useless, like tits on a bull, if you try to use them as absolute indicators of how thirsty your particular car is going to be. If you use those numbers for that, you’re gunna be disappointed – every time.

Car companies know fuel consumption is important to you, so they proclaim these official fuel test numbers loud and clear – they’re pumped up big and bold in all the marketing palaver, and the disclaimers are hidden away in the fine print – if they’re printed at all.

So – the regulations are out of step with reality, and car companies trumpet the numbers like there’s no tomorrow. 

Car companies also get very good at tweaking the engine tuning so that they ace the test. That’s a fudge.

You could easily buy into those numbers – only to feel gutted subsequently when the car fails to deliver them. What they should have done is design the tests to over-estimate fuel consumption – then every car would under-consume out there on the road, and everyone would live happily ever after. 

As a rule of thumb, you should take the official ‘combined cycle’ fuel number, and add about 30 per cent. That’s what your new car is actually likely to consume – if you’re a normal driver. More or less. More, if you’re a hoon.

At least the official fuel numbers are not outright lies. They’re a kind of institutionalized misrepresentation of actual fuel economy. Don’t let it form a pathological obsession with fuel, because that’s gunna feel like belting your head up against a brick wall.

If you’re thinking: lawyers at 10 paces, you probably don’t have a leg to stand on. Just accept it: the tests are rubbish.