How the Tesla Model S scored the highest-ever government safety rating

Iron Man strong.
Iron Man strong.
Image: Paul Sakuma/AP
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Apparently, the “S” stands for superlative.

Tesla Motors’s Model S electric sports sedan, which received Consumer Reports’ highest-ever automobile rating, now has scored “the best safety rating of any car ever tested” from the US National Highway Safety Traffic Administration (NHSTA), according to the Silicon Valley automaker.

The NHSTA awarded the Model S its highest rating of five stars for its ability to protect drivers and passengers from frontal crashes, side crashes and rollovers. But this being the company co-founded by tech overachiever Elon Musk, Tesla says the Model S actually received 5.4 stars.

“NHTSA does not publish a star rating above 5, however safety levels better than 5 stars are captured in the overall Vehicle Safety Score (VSS) provided to manufacturers, where the Model S achieved a new combined record of 5.4 stars,” the company said in a statement.

The ratings underscore the structural advantages electric cars have over gasoline-powered vehicles and the lengths to which Tesla has gone to make the Model S as safe as it is stylish.

With no gasoline engine block, the Model S sports a big front crumple zone that absorbs energy and protects passengers in a crash. The car’s massive battery pack sits underneath the passenger compartment, giving the Model S a low center of gravity that helps prevent rollovers—so much so that the company says that during testing technicians could not get the car to flip in the usual way. “Special means were needed to induce the car to roll,” according to Tesla.

To test a vehicle’s ability to withstand a side crash, a large pole is shoved into the vehicle. Tesla says 63.5% of the space around the driver was preserved compared to 7.8% of space for the Volvo S60, which also received a five-star rating in the test. “Tesla achieved this outcome by nesting multiple deep aluminum extrusions in the side rail of the car that absorb the impact energy (a similar approach was used by the Apollo Lunar Lander) and transfer load to the rest of the vehicle,” the company says. “This causes the pole to be either sheared off or to stop the car before the pole hits an occupant.”

And just how strong is the Model S’s roof, which is secured with aerospace-grade bolts? It broke a testing machine that was pushing down on the roof with the equivalent of the weight of four cars.