Consumers’ Checkbook was created due to an incompetent auto repair shop. In the early 1970s, Robert Krughoff, our founder, had just picked up his beloved Opel Kadett after its third stay with a mechanic for the same problem. While driving away, he realized he’d have to pull a U-turn and take it back again. He thought, “There should be a Consumer Reports for local services.” A few years later, his idea, born in frustration, became reality.

Fifty years later, car technology has improved greatly. Vehicles are safer and more reliable thanks to sensors that indicate possible mechanical problems, sturdier parts, collision avoidance capabilities, anti-lock brakes and traction control, smart suspensions, and more.

New cars are technological marvels, but they can’t fix themselves. But, just as Robert discovered 50 years ago, many shops still make their customers miserable by doing shoddy work, creating long delays, selling unnecessary repairs, and failing to provide accurate estimates.

Fortunately, not all shops stink. We evaluated more than 2,000 shops in seven major metro areas by surveying consumers, reviewing complaint records at government consumer agencies and the Better Business Bureau, using our undercover shoppers to collect thousands of price checks, and more.

Ratings from Customers

When they need car repairs, most consumers ask friends for suggestions. We surveyed Consumers’ Checkbook subscribers, plus a sample of other area car owners who we invited to participate. We found that many shops clearly make a lot of their customers miserable. Hundreds of the business that received 10 or more ratings on our surveys were rated “superior” for “overall quality” by fewer than 60 percent of their surveyed customers. But there are also many great shops out there: Many other shops were rated “superior” for overall quality by 90 percent or more of their surveyed customers.

Complaint Histories

While customers might have given shops less-than-rave reviews based on fairly minor issues, filing a formal complaint with a consumer agency usually reflects serious dissatisfaction.

We also checked for counts of complaints at local government consumer agencies and the Better Business Bureau (BBB). We found that consumer complaint information can be a meaningful indicator of quality: There is a correlation between the number of complaints and scores on our customer survey. Shops with no complaints on file were rated “superior” for “overall quality” by 86 percent of their surveyed customers, on average; shops with five or more complaints were rated “superior” for “overall quality” by only 65 percent of their surveyed customers.

New-Car Dealerships vs. Independent Shops

As you can see from the figure below, when we compare dealers to non-dealers on results from our surveys of consumers and on price, non-dealers scored better on all measures.

Our advice: Unless the work you need is covered by a new-car warranty or manufacturer recall, use an independent shop, not a dealership.

Except for getting free in-warranty repairs, there’s little reason to use a dealer’s repair shop. Many consumers falsely believe that dealer mechanics have access to proprietary knowledge, sophisticated diagnostic software, and better tools than independent garages. That’s not true. Both kinds of shops subscribe to the same databases that detail repair instructions, diagrams, and news from manufacturers. Although many car dealerships feature spacious, nifty-looking workstations, independents have access to the same tools and equipment.

Dealers’ quality scores may suffer somewhat because they tackle harder jobs. They argue that they get blamed for manufacturing defects, tend to work on new cars (which owners are pickier about), and get jobs too difficult for independents to handle. But after analyzing actual success rates on emissions-related repairs (as evaluated by state inspectors), we find independents perform substantially better than dealerships.

Mechanic Certification

Another way to gauge shop quality is to check on mechanic training. To become certified by the National Institute for Automotive Service Excellence (ASE), a mechanic must have worked in the automotive service field for at least two years and pass at least one of the tests offered by ASE. A technician can become certified in any or all of several automotive service categories. Certification is not easy—about one-third of the tests taken are failed—but according to ASE about 250,000 automobile repair technicians nationwide are currently certified. Technicians who pass eight of ASE’s nine automotive and light truck tests receive Master Technician certification, which nearly 55,000 mechanics across the country have. To remain certified, technicians must pass recertification exams every five years.

Because the ASE program seems well-conceived and well-managed, we advise you to use a certified mechanic. But keep in mind that while ASE certification may indicate competent mechanics, it doesn’t tell you anything about their diligence, honesty, or ability to communicate with customers.

AAA Approval

The American Automobile Association (AAA) approves shops by checking for a range of equipment and customer conveniences, staffing qualifications, quality control and environmental procedures, and complaint records at local consumer agencies. AAA Approved Auto Repair facilities must guarantee work they do for AAA members for a minimum of 24 months or 24,000 miles (whichever comes first) and agree to AAA-led arbitration of any complaints.

Although the AAA program appears to be well-conceived, AAA Approved shops were rated slightly lower than non-approved shops on our customer surveys. And AAA Approved shops may charge more than non-approved ones: Approved shops had slightly higher price comparison scores (described below), on average, than non-approved shops.

Business Practices

The best shops have procedures to foster good communication with customers and avoid disagreements.

One important policy is letting you speak directly with the technician who will be working on your car. Service write-up personnel at dealerships and large shops often know little about repairs, and may not be able to describe your car’s symptoms to a mechanic as well as you can. If you can’t easily explain a weird noise or problem, take the technician for a ride to point it out. A nationwide auto repair shop study found that vehicle return rates (to fix improper repairs) were about one-third lower if a customer had dealt with the repair technician rather than a service writer.

Also ask if the shop will let you test drive your car before you pay. This can help you avoid hassles if you find a problem later.

Finally, be sure the shop lets you follow basic good business practices—getting an estimate in advance, inspecting replaced parts, and receiving a detailed invoice. Local laws and regulations for the most part give consumers the right to demand these practices.

How Can I Check on Prices?

Because you often don’t know exactly what needs to be done until your car is at the shop, it’s difficult to determine whether the shop charges fair prices.

Our undercover shoppers called thousands of shops to get their prices for specific repairs (for example, replace the water pump for a 2016 Ford Focus SE using OEM parts). For many of the repairs we checked, some shops charged twice as much as nearby competitors.

A striking observation about the data we collected: Choosing a low-priced shop doesn’t mean you’ll get lousy work. In fact, low-priced shops were more likely to receive high marks from their surveyed customers than high-priced shops. We found that shops that charge the lowest prices were rated “superior” for “doing work properly on the first try” by 86 percent of their surveyed customers, on average, while shops with high price comparison scores received such favorable ratings from only 70 percent of their surveyed customers.

For more information on shop's prices, read our article on how to avoid getting taken for a ride.