Car dealers are failing to identify faults in their cars, according to thousands of owners surveyed Auto Express.

A little over a third of 61,000 people who took part in the magazine’s Driver Power 2015 study said this was the biggest complaint about the franchised dealer of their choice – it was the biggest issue amongst 22 of the 31 dealer networks rated.

The next biggest complaint was unanswered phone calls, at 28%. Following these were failure to explain a problem (15%), discourteous staff (11%), cars not being cleaned (8%) and unexplained bills (6%).

Lexus was voted as having the best dealers. The biggest complaint amongst its customers? Unanswered calls.

More than one in five survey respondents has had cause to complain to their dealer, and just 30% said they were happy with the response they got.

A total of 72% went to a franchised main dealer – up from 69% in 2014.

The main reason for this choice (26%) was that owners had bought their car there.

Recommendations from friends and cheap deals are on the up, while one in five decides to visit a dealership because they feel like they’re treated well. Expertise with a particular marque was also an important reason for choosing a dealer.

This year, dealers were polled in seven separate categories, including how helpful staff were, how clean the showroom appeared and the standard of work. Plus, our readers told us how long the work took and how expensive – or competitively priced – any repairs were, as well as rating franchises for their level of technical knowledge.

Best car dealers 2015 (“Biggest gripe”)

1. Lexus (unanswered calls)

2. Toyota (didn’t identify fault)

3. Jaguar (didn’t identify fault)

4. Honda (didn’t identify fault)

5. Peugeot (didn’t identify fault)

6. Subaru (didn’t identify fault)

7. Skoda (didn’t identify fault)

8. Porsche (unanswered calls)

9. Citroen (didn’t identify fault)

10: Mini (didn’t identify fault)

Worst car dealers 2015 ("Biggest gripe")

27. Seat (didn’t identify fault)

28. Chrysler Jeep (didn’t identify fault)

29. Nissan (didn’t identify fault)

30. Volkswagen (didn’t identify fault)

31. Suzuki (didn’t identify fault)

The middle ranks

11. Fiat

12. Renault

13. Dacia

14. Kia

15. Mazda

16. Alfa Romeo

17. Hyundai

18. Mitsubishi

19. Vauxhall

20. MG

21. Mercedes-Benz

22. Volvo

23. BMW

24. Land Rover

25. Audi

26. Ford