In a note posted without fanfare on its website, the National Highway Traffic Safety Administration did not mention Tesla by name, but clearly meant to rebut some of Tesla's fanfare, such as the company's statement that the results were the equivalent of 5.4 stars on a five-star scale.
"NHTSA does not rate vehicles beyond 5 stars and does not rank or order vehicles within the star rating categories," the agency said. "In addition, the agency has guidelines in place for manufacturers and advertising agencies to follow to ensure that accurate and consistent information is conveyed to the public."
Those guidelines would have kept Tesla from saying the Model S "set a new record for the lowest likelihood of injury to occupants," and that it's results "exceeded the safety score of all SUVs and minivans." Under its rules, NHTSA "strongly discourages the use of potentially misleading words such as 'perfect,' 'safest,' 'flawless' or 'best in class' to describe the star rating received by the vehicle." And it warns that companies shouldn't compare frontal ratings among vehicles if they're not in the same class or there's a weight difference of greater than 250 lbs., since the front ratings only reflect the safety of a collision with a similarly sized vehicle. (There's no prohibition with comparing side impact and rollover scores).
But Tesla explanation of its results stands up, and NHTSA can't do much more than assault Tesla with damp pasta. The agency has dominion over any part of a vehicle sold in the United States, from the headlamps to the owner's manual, but can't regulate the speech of a corporation or its employees. The non-binding guidelines derive from the agency's long-held worry about presenting consistent and easy-to-grasp safety ratings; there's an unspoken worry that if automakers start claiming bests and other superlatives, the whole idea of five stars being a top score would come into doubt.
NHTSA has long struggled to keep the five-star system relevant, and has considered toughening the tests because five-star scores have become routine. Tesla's announcement put more focus on NHTSA's crash safety than it's had in years, and until it can come up with a grading system that doesn't give half the class As, perhaps NHTSA should let the industry compete for extra credit and bragging rights.