Nearly half of all new car buyers are unhappy with the level of sales and aftersales service they receive from franchised dealers, according to the Which? Car 2002 report.

It found a huge gulf between the top and the bottom of the table, with Jaguar recording a 77 per cent satisfaction rating and Fiat scoring just 36 per cent.

“The story for servicing and repair is much the same, though a few manufacturers are putting more effort into making a sale than aftersales care. Mercedes-Benz, Saab and Daewoo all scored worse for servicing than they did for new car sales,” says the report.

Mercedes scored 65 per cent for sales but 56 for aftersales, while Daewoo scored 66 and 51 per cent and Saab 66 and 57 per cent respectively. However, the ratings only reflected how well owners thought they were treated by manufacturer's garages. When it comes to servicing and repair, this is only part of the story, says the report. “Our research over the last 30 years has consistently shown garages aren't doing a good job servicing cars,” it says.

“In mystery shopper surveys, we have found that garages routinely miss faults, charge for work they haven't done and recommend unnecessary repairs. Franchised dealers and independent dealers show the same poor level.”

Alan Pulham, RMIF franchised dealer director, says: “I'm not making excuses, but with 25 million cars on UK roads today, there is a lot of servicing work out there to be done and it is inevitable that some faults will be accidentally missed. But in some cases it is a matter of opinion between customer and garage as to what needs to be done and what the customer wants done.”

The survey gathered information on about 25,000 cars bought from dealers and asked Which? members where they bought the car and what they thought of the way their franchised garage treated them.