The Mercedes-Benz E class earned top honors among six large cars tested for crashworthiness by the Insurance Institute for Highway Safety in the U.S.
The E class qualified for IIHS' Top Safety Pick+, the group's highest award, by scoring "good" ratings in five crash tests.
The cars were subjected to tests for small overlap front crashes, moderate overlap front crashes, side impact crashes, roof strength and protection from head restraints.
"This group of large cars includes some with stellar ratings, but our small overlap front test remains a hurdle for some vehicles," David Zuby, IIHS' executive vice president and chief research officer, said in a statement.
Small overlap crashes account for about 25 percent of the serious driver injuries and deaths that occur in frontal impacts, IIHS says.
The Tesla Model S was among vehicles that missed the top safety rating after scoring "acceptable" on the small overlap front crash test and "poor" on the headlight test.
In the small overlap front crash test, 25 percent of a vehicle's front end on the driver side strikes a 1524mm (60 inch) barrier at 64 kph (40 mph).
The main problem with the Model S, IIHS said, was that the safety belt let the crash test dummy's torso move too far forward, allowing the dummy's head to strike the steering wheel hard through the airbag.
Tesla modified the belt in vehicles built after January, but IIHS said subsequent tests didn't resolve the problem.
