Real-world and official fuel economy gap grows

Research shows discrepancy in figures more than doubles in a decade and calls out worst manufacturers

Real-world emissions figures are around 25 per cent higher on average than car manufacturers say, according to research by the International Council on Clean Transportation (ICCT).

The gap has increased from 10 per cent almost a decade ago, and it’s the premium German makers that show the biggest discrepancy.

According to the data, which was based on fuel consumption data from nearly half a million private and company cars, BMW showed the biggest difference between real-world and test figures with a discrepancy of 30 per cent.

Audi followed this, with reported emissions around 28 per cent lower than actual figures. Meanwhile Mercedes showed a 26 per cent discrepancy between the two figures.

At the bottom of the table are Renault and Peugeot Citroen’s (PSA) whose figures show a 16 per cent difference between the ‘real-world’ emissions figures and those recorded in tests, while Toyota showed a difference of 15 per cent.

According to the report, the widening gap is costing motorists around 300 euros (£256) per years in fuel use.

The ICCT blamed the growing gap on three major developments. The first was the use of technology that shows a higher benefit in testing than real-world conditions – such as stop-start

There was also the use of ‘flexibilities’ in the testing procedure (taping up panel gaps, use of down-hill testing) and finally external factors by owners including increased use of air-con.

The European Parliament is currently attempting to push through a tougher testing procedure for 2017, but some EU member Governments are attempting to push this back until 2020.