Fuel consumption and CO2 join the concerns in diesel debate

News editor

The continuing scandal over emissions from Volkswagen’s diesel vehicles has started a discussion on the testing regimes for fuel consumption and CO2 emissions

This week’s National Air Quality Conference asks if diesel has a place in a zero/low emission future, a timely discussion given the controversy currently engulfing Volkswagen.

Since this story broke a number of commentators have put forward the view that Volkswagen is almost certainly not alone in taking advantage of the conditions in which emissions tests are done, and measures within the EU are set to be implemented next year to ensure that vehicles are tested on real roads as well as rolling ones.

One organisation calling for a comprehensive overhaul of the testing system is Transport & Environment (T&E), the green transport think tank that today extended the debate to fuel consumption and CO2 emissions in its 2015 Mind the Gap report.

They believe that distorted lab tests could be costing motorists around €450 (£330) in additional fuel costs compared to the marketing spiel published by automotive OEMs.

T&E say: “The gap between official and real-world performance found in many car models has grown so wide that it cannot be explained through manipulating tests known factors including test manipulations.

“While this does not constitute proof of ‘defeat devices’ being used to fiddle fuel economy tests, similar to that used by Volkswagen, EU governments must extend probes into defeat devices to CO2 tests and petrol cars too.”

The report states that the gap between official test results for CO2 emissions/fuel economy and real-world performance has increased to 40% on average in 2014 from 8% in 2001, and that without action this figure will reach nearly 50% by 2020.

T&E add that conventional cars can emit up to 40-45% more CO2 emissions on the road than what is measured in the lab, rising to over 50% for certain models.

Mercedes cars, they claim, have an average gap between test and real-world performance of 48% and the new A, C and E class models have a difference of over 50%. The BMW 5 series and Peugeot 308 are just below 50%.

The full analysis can be found at: 2015 Mind the Gap report.

The National Air Quality Conference takes place on October 1 at The Studio, Birmingham.