Fuel Consumption, Emissions Performance And Other Fairy Tales Photo:

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Tim O'Brien | May, 23 2016 | 6 Comments

First the Volkswagen Group, then Mitsubishi, and now most recently Suzuki (er… kind of), have admitted to fudging fuel consumption and/or emissions testing procedures on their cars.

Though it is yet to fully play out, and there are strongly held suspicions from a cynical public that more manufacturers will yet be found with their pants around their knees, the fines, class actions and damage to brands from these breaches has the potential to run to the tens of billions of dollars.

Even for giant transnational car companies, that’s gonna hurt.

Last month, Reuters reported that testing ordered by French authorities of a random sample of 100 diesel cars showed that 52 of those vehicles – from Renault, Fiat, Mercedes-Benz, Volkswagen, PSA Peugeot Citroen, Nissan, Opel and Ford – failed to fully comply with CO2 and NOX emissions regulations.

Nissan has also been named by South Korea over its diesel Qashqai SUV (to which Nissan has objected), and the US Justice Department is investigating Mercedes-Benz.

Above: Part of Volkswagen's emissions solution
Above: Part of Volkswagen's emissions solution

While Volkswagen, and possibly Mitsubishi, are likely preparing to swallow great gobfuls of bitter medicine about to be dispensed by governments and regulators, and, VAG in particular, are copping a savaging from outraged customers (with more than a bit of encouragement from an eager swarm of plaintiff lawyers), each has been quick - when sprung - to issue the public ‘mea culpa’ and each has moved quickly to rebuild trust with customers.

Emissions testing is one part of the matter, but, as the Suzuki revelation shows, there is the related matter of fuel consumption testing and how reliable are manufacturer’s claims.

GM US meanwhile has been forced (earlier this month) to temporarily withdraw the 2016 Chevrolet Traverse, GMC Acadia and Buick Enclave SUVs from sale in the US and Canada, and is now compensating up to 135,000 customers (with payments of US$450 to US$900), after discovering windscreen labels had overstated the fuel economy on these vehicles.

But no surprises here.

As a study published in Berlin in 2013 by the International Council on Clean Transportation (ICCT) reported, the gap between “official” and “real world” fuel-economy figures has reached more than 30 percent, whereas ten years earlier that gap sat at around 10 percent.

“All data sources confirm that the gap between sales-brochure figures and the real world continues to grow,” Dr. Peter Mock, Managing Director of ICCT Europe, said then. “Two years ago the gap was still around 25 percent. Now (2013) it has increased to 31 percent for private cars, and even higher for company cars.”

Of course, who among us actually believes that the car they are driving, in the way they are driving it, will get anywhere near the claimed official fuel consumption results (and we can only guess as to the emissions performance)?

Not me; I can rarely get near the claimed figures… maybe, on average, within 30 percent, and sometimes not within 50 percent.

That’s because the testing procedures, from jurisdiction to jurisdiction, are clearly flawed, clearly wide of real world conditions, and nearly impossible to replicate by any driver thrust into city traffic or sharing roads at highway speeds.

And the variation from the stated claims can sometimes be greater, or lesser, depending upon the badge on the nose (there is a research article in this, watch this space).

But car buyers, I would think, should be supplied information on fuel consumption and emissions performance they can trust. They should be able to rely on this information as at least ‘somewhat accurate’ when choosing a new car.

So, if there is one thing, among the many, that emerges from the shaming and public disgrace of companies caught manipulating results, it’s that the discussion has focussed attention on the testing procedures themselves. How reliable are they? How accurate should they be?

It is clearly time these procedures were overhauled by regulators. It is also time that the fuel consumption and emissions performance displayed on a windscreen be ridgi-didge, a real reflection of the car’s efficiency.

Can’t be too hard, can it?



The standard test for the fuel consumption and emissions performance label affixed to the windscreen of a new car is specified under Australian Design Rules (ADR) 81/02 Fuel Consumption Labelling for Light Vehicles. This label displays the fuel consumption and carbon dioxide (CO2) performance results for the vehicle.

The displayed values are obtained from a dynamometer test conducted under laboratory conditions, a uniform procedure specified in United Nations regulations to provide standardised results across jurisdictions for fuel consumption and CO2 emissions from light vehicles.

In other words, a standardised global standard, and subject to audit.

The test itself, devised during the 1980s and not originally intended for fuel consumption testing, is of just 20 minutes, divided into two phases.

Phase 1, the ‘urban’ cycle, represents conditions found in stop‐start traffic – in other words, accelerating, braking, accelerating again, repeated a number of times – and Phase 2, the ‘extra‐urban’ cycle, which involves the vehicle accelerating to a peak speed.

All done under controlled laboratory conditions, and on a dynamometer.

It’s not hard to see where the flaws might lie under such a laboratory process, and how the engine management of a vehicle under test might be set up to produce an optimum result.

MORE: Mitsubishi - Resignations Over Fuel Economy Scandal
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