IIHS launched its front crash prevention rating program in 2013 to help consumers sort through a maze of technologies and zero in on the most effective systems. The ratings are based on research by HLDI indicating that forward collision warning and autobrake systems help drivers avoid front-to-rear crashes at both low speeds and moderate speeds.

Under the three-tier rating program, models with optional or standard front crash prevention systems are rated as superior, advanced or basic. Ratings are determined by whether the vehicles have available autobrake, and, if so, how it performs in tests at 12 and 25 mph. The availability of forward collision warning also is factored in.

For a superior rating, a vehicle must have an autobrake system that can avoid a crash or substantially reduce speeds in both tests. For an advanced rating, a vehicle must have autobrake and avoid a crash or reduce speeds by at least 5 mph in 1 of 2 tests. Vehicles that have a warning system only earn a basic rating, provided the system meets National Highway Traffic Safety Administration performance criteria.

How the tests work

IIHS evaluates the stopping capabilities of vehicles equipped with autobrake in two tests at 12 and 25 mph on the Vehicle Research Center test track. In each, an engineer drives the vehicle straight toward a stationary target designed to simulate the back of a car. Since running into an actual car puts the test driver at risk and is expensive, IIHS uses an inflatable target as a stand-in. Under the vinyl cover, inflatable tubes and foam sit on a metal frame, which is then affixed to metal guides on the track to keep the target from moving until it is struck by the test vehicle. A GPS system and other sensors monitor the test vehicle’s lane position, speed, time to collision, braking and other data. An onboard camera captures each test run from the driver’s perspective and monitors any warnings issued by the front crash prevention systems.

The Institute awards points based on how much the systems slow the vehicle to avoid hitting the target or lessen the severity of the impact in the two tests. In the case of an unavoidable collision, lowering the striking vehicle’s speed reduces the crash energy that vehicle structures and restraint systems have to manage. That reduces the amount of damage to both the striking and struck car and minimizes injuries to people traveling in them.

To earn a point for forward collision warning, the system must meet NHTSA criteria. That means the system must issue a warning before a specified time in 5 of 7 test trials under three scenarios. The agency identifies vehicles with systems that meet the standard as part of its online ratings.

Point system

Vehicles can earn a maximum of 6 points for front crash prevention. Points are awarded as follows:

 12 mph
test
25 mph
test
Forward
collision warning
Speed reduction (mph)less than 55 to 910 or moreless than 55 to 910 to 2122 or moren/a
Points01201231

Models with 1 point earn a basic rating. A total of 2 to 4 points qualifies a vehicle for an advanced rating, and 5 to 6 points earns a superior rating.

Some vehicles advertised as having autobrake along with forward collision warning earn only 1 point and a basic rating if the autobrake fails to slow the vehicle enough to earn points in IIHS tests. If the Institute hasn’t tested a vehicle’s autobrake system, but NHTSA recognizes its forward collision warning system, the vehicle gets a rating of "basic; autobrake not tested."

Information on the availability of other crash avoidance features, not yet tested by the Institute, can be found here.