Screenshot via IIHS/YouTube
Compared with the 2017 Prius Prime and the 2017 Chevy Volt, the BMW i3 and the Tesla Model S weren't just safe enough to merit a "Top Pick +" by the IIHS, according to Road and Track.
"The IIHS is looking at a small overlap frontal crash, a moderate overlap frontal crash, side impact, roof strength, the head restraints, headlights and advanced front crash prevention," R&T Máté Petrány wrote.
The organization also assessed the vehicles' front-crash avoidance abilities; and their headlights.
The IIHS tested Model S vehicles built after October 2016 and according to its test results, the Model S fell short of the highest safety rating in a few key areas.
First, the driver's side seat belt didn't adequately restrain the occupant in a front overlap crash, causing the dummy's head to hit the steering wheel. Secondly, the roof of the Model S P100D that was tested wasn't strong enough to ensure safety in a rollover, due to the car's weight. The Model S earned an "acceptable" rating in these two categories.
Lastly, the organization gave the 2017 Model S a poor rating for its headlights.
Tesla is dealing with the seat-belt problem and is working with suppliers to fix the headlight issue, the IIHS said.
The automaker didn't immediately respond to Business Insider's request for a comment on the IIHS findings.
The BMW i3 also had a problem in the small frontal overlap crash scenario: the vehicles couldn't fully protect passengers in the rear seats.
The Chevy Volt and the Prius Prime plug-in both scored higher on the IIHS's tests.
Check out the full results below.