Subaru, Cadillac, Mercedes and Volvo vehicles earned top marks in a first-of-its-kind crash test of models equipped with systems to help drivers avoid rear-end crashes.
The tests, conducted by the Insurance Institute for Highway Safety, rated "active safety systems," which warn drivers of an impending impact and, in some models, automatically hit the brakes. The systems rely on radar, cameras and lasers that measure distances from other vehicles or fixed objects.
To judge automated braking systems, the insurance group put each model through a series of five test runs at speeds of 12 and 25 mph on the track at the Vehicle Research Center in Ruckersville, Va.
An engineer drove the vehicle toward a metal-framed target designed to simulate the back of a car. Sensors in the test vehicle monitored its lane position, speed, time to collision, braking and other data.
But the tests demonstrated that most manufacturers still have work to do in perfecting the systems.
The insurance trade group, for instance, found only minimal braking at 12 and 25 miles per hour in tests of the Infiniti JX SUV. The Toyota Prius V wagon scored so poorly that it didn't qualify for the institute's front crash prevention rating.
But Subaru's EyeSight collision-avoidance system prevented the automaker's Legacy and Outback models from hitting a target vehicle in both the 12 mph and the 25 mph tests, the insurance research group said.
Cadillac's Automatic Collision Preparation helped the General Motors brand's ATS and SRX avoid hitting the target in the 12 mph test. In the 25 mph test, the systems reduced the ATS' speed by 15 mph and the SRX's speed by 19 mph. Both the Subarus and the Cadillacs received "superior" test ratings.
"Front crash prevention systems can add $1,000 or more to the cost of a new car. Our new ratings let consumers know which systems offer the most promise for the extra expense," said David Zuby, the institute's chief research officer.
So far, the institute has tested 74 midsized cars and sport utility vehicles from the 2013 and 2014 model years. In addition to the seven that got superior ratings, eight earned "advanced" ratings. The systems on those vehicles reduced the speed at which crashes occurred but did not prevent collisions.
An additional 31 models earned "basic" ratings. They are equipped with a system that alerts the driver to the risk of a crash but don't automatically trigger the brakes.