The Tesla Model S is again Consumer Reports' top-rated ultra-luxury sedan after the automaker updated its software to include automatic emergency braking at highway speeds. 

Earlier this month, CR’s Tesla Model S received an over-the-air update that moved the upper limit of the AEB system from 28 mph back to 90 mph, like Teslas built before October 2016.

CR’s engineers then verified at our test track that the AEB operated at higher speeds by driving the electric Model S at a target that mimics the back of a car. We also verified that Tesla had sent the software update to its other cars by checking online forums and inspecting cars at Tesla dealerships.

The Tesla Model X SUV also regained some points, but those did not lift it very much in its category, where it resides near the bottom.

How Did We Get Here?

On April 26, CR lowered its scores for the newer versions of the Model S and Model X vehicles because they didn't have their AEB system enabled. While the hardware was built into cars produced after October 2016, the safety feature was not enabled as part of the "standard" package.

Based on outside research and our own testing, CR believes that AEB has helped save lives. Because of that, CR awards extra points to the overall score to vehicles that provide automatic braking as a standard feature across all trims.

Twenty U.S. automakers, joined a voluntary agreement with the National Highway Traffic Safety Administration in March 2016 to make AEB standard on every trim level of most light vehicles starting in 2022.

"Automakers should never treat safety as a luxury item," says William Wallace, a policy analyst for Consumers Union, the policy and mobilization arm of Consumer Reports. "Proven, life-saving safety features should be in every new car sold, and automakers certainly should not wait until 2022 to make automatic emergency braking standard."

AEB was missing on versions of the Model S and Model X built after Oct. 19 because Tesla started using its own technology for the feature after parting ways with a supplier. The company told CR that it was working on rolling out the necessary software to support AEB, and targeted the delivery time as the end of 2016. When that date passed, Tesla said the safety features were coming soon, but didn't give a specific timeline.

On April 21, CR informed Tesla that it planned to lower the ratings for the two models. Tesla began sending over-the-air software updates on April 26. CR’s Model S received its AEB update the next day.

The update activated AEB on vehicles up to 28 mph, not to the higher limit of 90 mph on earlier versions of Tesla models that had AEB. On April 26, Tesla said that AEB would eventually work at highway speeds, which led to the recent update.