Dealers have been criticised by another Which? survey which shows sales executives’ lack of knowledge about the cars they are selling.

Undercover researchers posing as potential customers asked 16 dealers three safety questions and found that one in four sales executives answered all of them satisfactorily. The unnamed dealers were tested on their product knowledge for a Ford Focus 1.6 Zetec, Peugeot 307 1.6 S, Nissan Qashqai 1.6 Accenta and a Vauxhall Astra 1.6 Club.

The three questions asked were: “Can I carry a six-month-old baby on the front passenger seat?”, “I’ve heard that electronic stability control is important, should I get my car fitted with it?” and “I’ve heard about active head restraints. What are they and does this car have them?”.

In the examples Which? gave, some dealers were unsure of which models had ESC as standard, the procedure for turning the front safety passenger airbag off and confused about what active head restraints were.

A Ford spokesman said: “Our training covers ESP and driver and passenger protection was covered just as thoroughly, including the child protection, passenger airbag deactivation and other safety elements.”

 Ford said it would continue to work to improve sales teams’ product knowledge further in partnership with its dealer network.

A Vauxhall spokesman said the legal side of explaining safety equipment can be confusing for anyone.

Nissan and Peugeot said they offered training courses for dealer staff to ensure they were up to date with product knowledge.