Consumer Reports ranks cars using two methods: First, it sends out surveys to ask consumers about the overall performance of their vehicles. Second, it checks this data against its own tests, which are conducted on a test track.
Consumer Reports annually collects its data from a questionnaire that is mailed to subscribers of both its Web site and its magazine. In 2009, the survey was sent to 7 million subscribers, and 1.4 million responses were received [source: Consumer Reports]. The survey is created by a staff of social scientists who also consult with automotive engineers and statisticians at the Consumer Reviews' national research center.
The survey asks subscribers to report any problems they've had with their vehicles during the past 12 months. They're told to categorize problems by level of severity according to cost, safety, failure or time without a vehicle. Although subscribers also may report problems covered under warranty, they may not report damages or items under recall. Subscribers also are told not to report issues that are due to normal wear and tear, like issues related to batteries or brake pads, unless they failed much earlier than expected. This "reliability data" is updated annually.
After survey results are tabulated, engineers then test the vehicles on the Consumer Reports Test Track. They run a series of 50 performance tests to check against the data from the 1.4 million subscribers from whom they've collected data.
To maintain their goal of subjectivity, Consumers Union, the owner of Consumer Reports, purchases the cars for testing. Once they're on the track, the cars are driven through various courses that include straight tracks, skid pads, rock hills for off-roading and sharp turns to test for handling. Engineers look at how well cars accelerate, brake and ride, and they also check up on safety, fuel economy, comfort and cargo volume. They compare the data collected from the survey with their own findings on the track.
Additionally, in order to test transmissions, engineers drive vehicles through miles of city and country roads and high-speed interstates. While driving, they make hard stops and sharp turns to see how well vehicles respond to shifts in speed and direction.
Both parts of the test are very important. For example, while a car might perform quite well on the test track, it may get bad reviews from people dealing with the vehicle on a daily basis. The combination of reliability data and performance tests helps to inform consumers about the best vehicle for them.
For more information about types automotive ratings, read on to the next page.