NHTSA tells Tesla there's no such thing as a 5.4-star crash rating

In August, Tesla Motors announced that its Model S electric vehicle had received the highest safety rating in the United States, achieving "a new combined record of 5.4 stars" based on crash test data. There's only one problem with that: the US National Highway Transportation Safety Adminstration, which conducts those tests, doesn't give ratings over five stars — period. So today, the NHTSA is attempting to set the record straight, revising its advertising guidelines to forbid automakers from ...