The “Mind the Gap!” report was published earlier this month, with T&E commissioning the Dutch consultancy TNO to measure fuel consumption and CO2 emissions on six standard new cars using the official test procedures. On average, TNO found the results of their tests to be 23% higher than the official figures presented by carmakers.

T&E says the data ‘demonstrates that the current (NEDC) test is outdated and unrepresentative of real-world driving and current vehicles, and that lax testing procedures are allowing car-makers to manipulate the official tests to produce unrealistically low results’.

As a result T&E says the current test regime should be replaced by a new test in 2016, and follow-up checks should be carried out on cars to show their results are consistent with the official test results.

According to Mind the Gap!, there are about 20 ways that carmakers 'creatively reinterpret' test procedures to make fuel consumption and CO2 emissions lower (CO2 emissions are directly linked fuel consumption). Among the techniques used are:

• Taping over cracks around doors and grilles
• Overinflating the tyres
• Adjusting the wheel alignment and brakes
• Using special super-lubricants
• Minimising the weight of the vehicle
• Testing at altitude, at unrealistically high temperatures and on super-slick test tracks.

T&E cars officer Greg Archer said: ‘It’s clear the current test regime is not fit for purpose. Consumers’ trust in official information and regulation is breaking down, because what it really costs the consumer to run a car is a quarter more than the official test results say. The only way that trust can be restored is for the loopholes to be closed.’

The organisation says that the World Light Duty Test Procedure (WLTP) could be used as an alternative testing procedure. This has been developed as part of the work of the United Nations Economic Commission for Europe (UNECE) and is aimed at enabling consumers to get a more realistic picture of vehicles’ real fuel consumption.

T&E director Jos Dings added: ‘Car makers are not doing anything illegal, but they don’t have to – the rules are so lax that they can manipulate the results within the guidelines. In doing this, they’re not just cheating the regulations but they’re also deceiving their customers. This situation benefits no-one and must be resolved.’