Matthew Carrington, chief executive of the Retail Motor Industry (RMI) has said he is “extremely surprised by the latest What Car? survey into garage standards”.

Tommorow WhatCar? will publish the results of an investigation into standards of service in the retail motor sector. Using vehicles with deliberately placed faults, the magazine set up mystery shopping exercises at a number of independent garages, franchised dealers, and fast-fit centres.

The total size of the sample was 30 garages.

Carrington said: “It is amazing that such a well-respected publication should base their results on such a limited survey of the retail motor sector. Samples of 10 independents, franchised dealers, and fast-fit centres can in no way characterize the standards of a sector many thousands strong.

“Obviously we do not condone bad service by any garage, and clearly those that failed to provide an excellent service need to look at their practices, but to make a judgement about the whole industry from these isolated examples is wholly unhelpful.

“A truly representative survey would have to take a sample of hundreds of businesses from right across the UK.”