The National Highway Traffic Safety Administration is taking exception to Tesla Inc.’s characterization of the agency’s safety ratings.

On Sunday, Tesla Inc. (TSLA.O) released a lengthy blog post saying that it engineered the Model 3 to “be the safest car ever built” and that NHTSA’s tests show that it has “the lowest probability of injury of all cars the safety agency has ever tested.”

But in a statement Tuesday, NHTSA said that its crash tests combine into an overall safety rating and that it does not rank vehicles that score the same ratings.

“A 5-star rating is the highest safety rating a vehicle can achieve,” the agency said in the statement, which did not name Tesla. “NHTSA does not distinguish safety performance beyond that rating, thus there is no ‘safest’ vehicle among those vehicles achieving 5-star ratings.”

Tesla’s Model 3 received five-star ratings in frontal and side crash tests, rollover prevention and overall. The 2018 Ford Mustang, Honda Accord, Subaru Impreza and Legacy and Toyota Camry also scored five stars in those categories in the most recent batch of agency testing.

NHTSA guidelines for the use of its crash test results in advertising and communications warns that using terms such as “safest” and “perfect” to describe a particular rating or an overall score are misleading.

Companies that make wild claims about NHTSA crash test ratings can land in hot water with other authorities, such as the Federal Trade Commission. NHTSA’s guidelines warn that the agency may refer “knowing misstatements or mis-characterizations” of NHTSA crash test ratings to other state or federal agencies.

NHTSA issued a similar statement in 2013, when Tesla said that its Model S achieved a vehicle safety score equated to 5.4 stars.