The Tesla Model S has lost its top ranking from Consumer Reports.
The magazine said Wednesday it has lowered its score for the basic Model S, a luxury, all-electric sedan, because an automatic braking feature has yet to be activated by a software upgrade as promised.
"When we purchased our latest test car, we were assured automatic emergency braking would be enabled by the end of 2016," Jake Fisher, director of Consumer Reports' Auto Test Center, wrote in a review. "We've been waiting for this important safety feature, which is standard equipment on much cheaper cars."
Consumer Reports has been a big fan of the Model S. The magazine once called it the best car it had ever tested, and it gave a higher-end version of the sedan its first perfect score ever.
The magazine said that Tesla promised the software update would come Thursday. But that wasn't fast enough to saving its score in the annual rankings.
"A prospective Tesla buyer late last year might have considered a short delay a minor inconvenience," the magazine wrote. "But now someone who bought a Tesla with advanced hardware after October has been driving without the safety feature for roughly half a year."
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Tesla (TSLA) did not immediately respond to a request for comment.
The score of 85 for the basic version of the Model S ties it for second place in the Consumer Reports rankings for ultra luxury cars. The BMW 7 Series also got a score of 85. The Lexus LS was given a score of 87.
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Tesla's Model X also had its score lowered because of the auto braking delay. But it has a much lower score of 56, placing it near the bottom for luxury midsize SUVs.
