The change by the National Highway Traffic Safety Administration was
prompted by Tesla Motors Inc., the Palo Alto electric car company. Tesla has
promoted its electric Model S as the safest car in America, saying it
earned a 5.4-star rating from the government.
The new guidelines stress that NHTSA doesn't give crash-test ratings higher
than five stars. The agency says automakers who claim ratings higher than
that are misleading the public.