Fleet News

Makers of premium cars exploit emissions tests the most, claims report

fuel pump prices

Premium car manufacturers in Europe manipulate fuel economy figures in tests much more than those makers that produce more mainstream vehicles, a new report by the International Council on Clean Transportation (ICCT) reveals.

The report adds new evidence to a series of recent studies that show the gap between official test results and the fuel consumption drivers experience on the road is rapidly increasing year-on-year.

The study compares, for the first time, the progress made by carmakers on official and real-world fuel consumption over the last ten years in Europe.

Luxury car brand BMW captures top-spot, reporting fuel efficiency figures that are on average 30% lower than in real-life. This means that a buyer of a typical BMW car will burn on average around a third more fuel than claimed in the brochure and on labels in dealerships.

Audi ranks second with a ‘real v. claimed’ gap as wide as 28%, followed by Opel/Vauxhall (27%) and Mercedes (26%). At the bottom of the table, Toyota’s manipulation of emissions tests produces official fuel economy figures that are just 15% lower than the real-world performance of its vehicles, while Renault’s and Peugeot Citroën’s (PSA) figures are on average 16% lower.

In 2005, the difference between reported and real-world fuel consumption for BMW was 12%. By 2011, this gap had more than doubled, rising to 30%. In comparison, Peugeot Citroën, producer of smaller vehicles, saw its gap increase from 12% to 16% over the same period. This suggests that the growing difference cannot be attributed to a change in driving style, but rather to further manipulation of test results by carmakers.

On average, new cars’ official fuel efficiency figures are about 25% lower than their real-world fuel consumption. ICCT’s analysis also shows just 2% of German drivers matched the official fuel economy figures in 2011.

Transport & Environment clean vehicles manager Greg Archer said: “Car buyers in Europe need reliable fuel consumption figures to make informed purchase decisions. Carmakers aren’t delivering. European politicians need to end the current manipulation of fuel economy data.”

Car manufacturers measure vehicle fuel consumption and CO2 emissions through a system of testing called the New European Driving Cycle (NEDC). This test cycle is out of date and unrepresentative and contains many loopholes that carmakers are increasingly exploiting to fiddle the official figures at the expense of consumers’ trust. A new global testing system, called World Light Duty Test Cycle and Procedures (WLTC/P), which will be finalised in 2014, is more robust and representative of real-world driving. The European Parliament and European Commission propose to introduce this improved test in 2017. This decision is currently being discussed among member states of the European Union.

Archer added: “The current test is over 30 years old and unrepresentative of real-world driving conditions. The lax testing rules allow carmakers to claim unachievable fuel economy. The European Commission and the European Parliament proposed to tackle this issue. EU member states should support them to ensure cheating of drivers stops.”

Login to comment


  • Chris Derbyshire - 29/05/2013 10:15

    Manufacturers of 4 wheel drive vehicles (not just off road) are permitted to disconnect one of the prop shafts to allow a 2wd economy figure. Secondly, the engine temperature has to be low when running a retest on the same day. Some manufacturers, fast cool the engine with fans leaving the transmission at operating temperature thus reducing the energy to get it there. If some marques do not do this, their 4x4 saloons /SUVs can look too good to be true!

  • Andrew Baker - 29/05/2013 15:10

    This comes as no surprise having a company car that is supposed to acheive 72mpg, best i have ever been able to acheive is 64mpg and that is driving like on an eco drive, not keeping up with the motorway traffic, ie on a motorway rather than doing 70mph doing 55 mph, even lorries are overtaking me when trying to acheive the official fuel consumption figures

  • GrumpyOldMen - 30/05/2013 14:23

    Slight surprise in that in our experience, BMWs are actually one of the few that do pretty much what it says on the tin. Unlike Audis. When WLTC/P adopted, will the chancellor lower the BIK rates several bands do you think?

Compare costs of your company cars

Looking to acquire new vehicles? Check how much they'll cost to run with our Car Running Cost calculator.

What is your BIK car tax liability?

The Fleet News car tax calculator lets you work out tax costs for both employer and employee