Three new models crucial to resurgent U.S. automakers received positive, four-star ratings in U.S. government crash-safety tests that were toughened in response to concerns voiced by safety and consumer groups. The news was less encouraging for Toyota Motor Corp. Its Camry, the best-selling vehicle in North America, earned an average three stars and was outperformed by virtually every other vehicle included in a first analysis of 2011 models conducted by the Transportation Department.