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. Theres only one problem with that: the US National Highway Transportation Safety Adminstration, which conducts those tests, doesnt 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 stating that a car received a higher score. The new advertising guidelines actually dont explicitly mention Tesla, and theyre really not solely targeted at the electric automaker at all.