Manufacturers will be prevented from making misleading claims about fuel consumption after a complaint was upheld against Audi.
The German carmaker had advertised the Audi A3 TDI as “the most fuel efficient Audi ever” achieving “a quite remarkable 68.9mpg on a combined cycle”.
However, the Advertising Standards Authority (ASA) received a complaint from somebody who had bought the car and had been unable to achieve that fuel consumption.
Audi told the ASA that fuel consumption figures did not give an accurate representation of the actual fuel consumption which could be expected from any particular vehicle and were provided only to enable comparisons between different vehicles or models.
Fuel economy figures are based on rolling road tests in laboratory conditions carried out in accordance with European regulations.
However, the ASA upheld the complaint against Audi and it will now force carmakers to include a disclaimer in adverts to explain that quoted mpg figures may not reflect real-world performance.
“This is a significant ruling that draws a line in the sand,” said an ASA spokesman.
“It is not just about Audi. It sets a precedent that will have ramifications for other car manufacturers.
“The ruling sets out quite clearly that qualification is needed when quoting mpg figures. There will be an industry-wide communication to manufacturers and trade associations so they are aware of what to expect in future.”