The Transportation Department is outlining changes Tuesday to the government's 5-Star Safety Rating System that will make it more difficult for new cars and trucks to earn top scores.
Only two of the first 34 vehicles tested under the new program the 2011 BMW 5 Series and a version of the 2011 Hyundai Sonata received the top grade of five stars. The Toyota Camry, the best-selling passenger car in the United States, received three stars.
The ratings range from one to five stars, with five stars being the highest and one star being the lowest.
The so-called "Stars on Cars" system, which evaluates vehicles on front-end and side-impact crashes and rollovers, was started in 1979 and has helped generate interest in safety equipment such as side-impact air bags and anti-rollover technology. But the program is being revamped for the 2011 model year because so many vehicles were receiving top marks under the old system, making it difficult to distinguish the best performers.
Typically, more than 90 percent of the vehicles tested under the old system earned four or five stars. In 1979, less than 30 percent received four or five stars.
"More stars equal safer cars," said Transportation Secretary Ray LaHood. "Through new tests, better crash data and higher standards, we are making the safety ratings tougher and more meaningful for consumers."
The new system adds an overall score and takes into account crash-prevention technologies and a new test that simulates a car striking a pole. The overall score combines the results of front, side and rollover tests and compares those results with average risk of injury and the potential for vehicle rollover of other vehicles.
In the latest testing, most of the 33 vehicles reviewed received an overall score of four out of five stars. The 2011 Nissan Versa got two stars while hybrid and conventional versions of the Toyota Camry received three stars. Another 22 vehicles will be tested later this year.
Last year's Versa was given solid 4-star ratings in all crash tests. The 2011 model received only 3 stars in frontal and side impact tests.
The Alliance of Automobile Manufacturers, which represents General Motors, Toyota, Ford and other auto companies, said the changes will mean the ratings found on new car labels will probably go down, even in cases where there have been no significant changes to the vehicle.
The trade group said the changes won't allow consumers to compare the scores of vehicles built in the 2010 model year or earlier to new 2011 cars and trucks. Many 2011 vehicles that have not been tested will be labeled as "not rated" or "to be rated," the auto alliance said.
Prior to releasing the results for the new testing system, the National Highway Traffic Safety Administration (NHTSA) warned that the marks may show a slight decrease in safety for some vehicles due to the stricter criteria - but that it should not be taken as a sign that the cars were less safe, just being tested more rigorously.
"Because of the more stringent tests, 2011 model ratings are not comparable to 1990-2010 vehicles," said a statement on the highway safety agency's website. According to NHTSA, the new tests "provide more information about safety feature performance and crash avoidance technologies."