Making cars safer is like chasing the horizon. The tougher the tests get, the better the cars get at acing them.

Nearly three-quarters of vehicles tested by IIHS' tougher front-crash prevention tests earned good or acceptable ratings.

The original vehicle-to-vehicle front crash prevention test was run at 12 and 25 mph (20 and 40 kph) with a passenger car target in the center of the travel lane. It was discontinued at the end of ...