JohnCarey

DODGY DATA

John Carey

RELIABLE DATA IS A VALUABLE COMMODITY. IT’S THE BEDROCK THAT UNDERLIES SOUND DECISION MAKING. SO IT IS ESPECIALLY TROUBLING TO LEARN THAT THE BEST INFORMATION WE HAVE ON THE RELATIVE CO2 EMISSIONS OF CARS ON SALE TODAY COULD BE DODGY. LOW NUMBERS, IT TURNS OUT, MIGHT REFLECT A CARMAKER’S WILLINGNESS TO CHEAT MORE THAN ITS ENGINEERING EXPERTISE.

Soon after the Volkswagen emissions scandal began to make headlines last September, Germany’s biggest carmaker confessed to also manipulating the results of tests to determine the official CO2 g/km output of some of its cars. The amount of this major greenhouse gas a car produces is directly proportional to how much fuel it burns (and also what that fuel happens to be).

This relationship makes CO2 numbers much more relevant to the typical car buyer. They’re a proxy for fuel consumption, and this is a factor almost guaranteed to influence any purchase decision. The same can’t be said for NOx emissions, which was what Volkswagen was initially caught cheating on.

Where clever software was used to achieve deceptive results in testing for NOx, the methods reportedly adopted by VW to obtain lower CO2 numbers were very simple. In fact, they were pretty much exactly what a keen competitor in a pretty much exactly what a keen competitor in a fuel-economy run might do; pumping up tyres to reduce rolling resistance, for example.

There’s more pressure to deliver low CO2 numbers in Europe than anywhere else.

Compliance with European Community regulations depends on them, and the tax systems of most countries in the community have some kind of incentive for buyers to choose a car with lower CO2. These can include tax breaks at purchase time, lower annual road taxes and more.

None of these factors are in play in Australia. At least not yet. But we do borrow Europe’s standards as the basis for Australian Design Rules covering emissions standards (ADR79) and the calculation of fuel consumption and CO2 (ADR81).

In the past I would argue that even if ADR81 data couldn’t provide an accurate guide to a car’s real-world fuel consumption, it could at least indicate whether a particular model was better or worse than its competitors. Now I’m not so sure.

Especially after analysing some good data.

Italian monthly Quattroruote has been drawing attention to the discrepancy for years and grabbed the opportunity to raise the issue again following the VW scandal. It published a list of the 160 diesel, petrol and hybrid cars tested by the magazine since January 2014, highlighting the difference between official CO2 numbers and what they actually achieve. Quattroruote does this sort of thing really well, using their publisher’s track and facilities outside Milan for controlled, repeatable testing.

Not a single car equalled its official CO2 number. Not one. The range of overshoot was immense, from 8 to 72 percent higher. However, the data contained something even more interesting. The 13 cars in the low end of the deviation – 25 percent increase or less – were from all over the world; Europe, Asia and the US.

But the worst 16 offenders – above 60 percent increases – were all from Europe.

Volkswagen isn’t the only European carmaker getting cheaty with CO2, it seems safe to say…

Not a single car equalled its CO2 number, and the worst offenders were all from Europe

Rising gases

Worst among the 160 cars tested by Quattroruote was the BMW X6 xDrive 30d, with CO2 emissions (and fuel consumption) that were 72 percent higher than the homologated fi gure. But the magazine’s data also showed some makers’ numbers are consistently closer to reality than average.

Mazda was one brand that stood out for this reason, followed by Skoda.