Complaints about used cars bought from independents topped the new Citizens Advice helpline which launched in April this year.
Of the 150,000 calls made in the first month, 12,000 or 8% were about used cars bought from independents.
The figure was three times the amount received about used cars bought from franchised dealers and from private sales.
The advice bureau said most complaints were related to the car itself and then misleading information about the car.
Industry bodies have responded to the CAB statistics.
The Independent Garages Association (IGA) said the stats highlight the importance of buying from a "reputable and approved used car garage".
IGA director Stuart James said: "As the representative voice for the independent garage sector, we acknowledge the high levels of consumer complaints that have been made to the CAB. However, the IGA ensures that all of its members adhere to a strict code of practice backed by an arbitration and conciliation service for consumers.
"In addition, the IGA provide a consumer garage finder website (trustmygarage.co.uk) that lists all member sites which have undergone a rigorous audit.
"As a trade body we are confident of their quality standards and offer ‘a consumer reassurance scheme’ up to a value of £1,000 should a complaint be justified."
Chris Mason, Motor Codes managing director, said: “Despite the vast majority of garages and car retailers upholding the very best service standards, these figures are impossible to gloss over and demonstrate why some consumers are nervous about buying used cars.
"One of the most important pieces of advice offered by Citizens Advice is to find a reliable retailer, to seek recommendation and to find a seller that operates to an existing motor industry code of practice.
“Motor Codes currently offers consumers an online garage finder and customer review facility for thousands of garages across the UK committed to our New Car and Service and Repair codes of practice and, if asked, we will work with Citizens Advice to explore the most effective way of directing people to responsible used car sellers."
The full top 10 consumer complaints between April and June 2012 were:
1. Used cars bought from an independent dealer
2. Problems with upholstered furniture
3. Mobile phone contracts
4. Repairs from an independent garage
5. Problems with women’s clothing
6. Mobile phone handsets
7. Building work
8. Troublesome TVs
9. Lap-tops, notebooks and tablet PCs
10. Second hand cars bought from a franchised dealer
Citizens Advice chief executive Gillian Guy said: "If you’re not a motor head, stepping onto a used car dealer’s forecourt can feel like entering a lion’s den.
"But there are things consumers can do to protect themselves, like looking out for unusually low mileage on an old car, which could mean it’s been tampered with.
“The Citizens Advice consumer service and local bureaux are at hand to help people with their consumer problems. And we also have practical information to guide consumers through big purchases – like buying a car or signing up to a mobile phone contract.”