RAC Cars News


Research Condemns Fuel Economy Statistics

By raccars Published

Image Source

Fuel economy has become an increasingly important factor determining buyers' choice of vehicle, however there have been rumblings for some time that the officially stated figures have proved impossible to achieve in the real world.

As a result, the ICCT (International Council on Clean Transportation) has conducted extensive investigation that has revealed discrepancies of up to 25%. Furthermore, the difference between manufacturers' stated fuel economy figures and those resulting from real world tests has more than doubled in the past ten years. A decade ago fuel economy performance as stated by manufacturers was 10% higher than actual figures, while the latest research claims statistical abuse of up to 25%.

The ICCT has deemed premium German manufacturers the worst offenders, according to information gleaned from tests on almost 500,000 vehicles, both privately owned and company cars. BMW was at the top of the list,, stating fuel economy performance statistics 30% higher than drivers could coax from their vehicles in real world conditions. The ICCT's second worst offender was Audi with a 28% difference in emissions compared to those officially given, then Mercedes with 26%.

The big French companies came in for slightly less condemnation, with PSA (Renault, Peugeot and Citroen) showing emissions discrepancies of 16% and Toyota slightly better still at 15%.

The ICCT's concern is focused upon the effect on motorists, who potentially stand to lose more than £250 per annum on extra fuel by choosing a vehicle based upon manufacturers' stated efficiency figures.

Investigations concluded that there were three significant factors responsible for the discrepancy in figures. Firstly, manufacturers are increasingly basing their conclusions upon advances in modern technology such as stop/start ignition systems, which show distinctly lower benefits in real world driving than in the conditions of a test track.

Secondly, the test programmes offer a series of loopholes that manufacturers can exploit to return the maximum fuel economy figures. These include putting tape over panel gaps to create unrealistic aerodynamic performance or excessive downhill test routes.

Test procedures thirdly fail to take into account external, user dependent variables such as the use of air conditioning or other auxiliary features.

However the Council hopes that plans to impose more rigid testing conditions will be approved by the European Parliament. The updated test procedures are expected to come into use in 2017, dependent upon the acquiescence of a few representatives of EU member countries who are moving to delay the new regime until 2020.

Looking to Buy?
Search for cars