Arlington, Virginia -- September 30, 2013 -- A new test program by the U.S.-based Insurance Institute for Highway Safety (IIHS) rates the performance of front crash prevention systems. The rating system is based on research by the Highway Loss Data Institute (HLDI), indicating that forward collision warning and automatic braking systems are helping drivers avoid front-to-rear crashes.
The Institute rates models with optional or standard front crash prevention systems as superior, advanced or basic depending on whether they offer autonomous braking, or autobrake, and, if so, how effective it is in tests at 12 and 25 mph. Vehicles rated superior have autobrake and 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.
To earn a basic rating, a vehicle must have a forward collision warning system that meets National Highway Traffic Safety Administration performance criteria. For a NHTSA endorsement, a system must issue a warning before a specified time in 5 of 7 test trials under three scenarios.
Moderately priced and luxury midsize cars and SUVs are the first to be evaluated in the new IIHS test program. These include 74 vehicles, all 2013-14 models. Seven earn the highest rating of superior when equipped with optional autobrake and forward collision warning systems. They are the Cadillac ATS sedan and SRX SUV, Mercedes-Benz C-Class sedan, Subaru Legacy sedan and Outback wagon, Volvo S60 sedan and XC60 SUV.
Six models earn an advanced rating when equipped with autobrake and forward collision warning. These include the 2014 Acura MDX SUV, Audi A4 sedan and Q5 SUV, 2014 Jeep Grand Cherokee SUV, Lexus ES sedan and the 2014 Mazda 6 sedan. In addition, the Volvo S60 and XC60 earn an advanced rating when they aren't equipped with an option called Collision Warning with Full Auto Brake and Pedestrian Detection. The S60 and XC60 are the only models in the new test program with standard autobrake. Called City Safety, the system brakes to avoid a front-to-rear crash in certain low-speed conditions without warning the driver before it takes action.
Twenty-five other vehicles earn a basic rating. Three models available with forward collision warning earn higher ratings when equipped with autobrake. They are the 2014 Acura MDX and the Cadillac ATS and SRX. Thirty-six models either don't offer a front crash prevention system, or they have a system that doesn't meet NHTSA or IIHS criteria.
Test track evaluations
To gauge how autobrake systems from different manufacturers perform, the Institute conducted a series of five test runs at speeds of 12 and 25 mph on the track at the Vehicle Research Center in Ruckersville, Va. In each test, an engineer drove the vehicle toward a stationary 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. The IIHS protocol is similar to the procedure the European New Car Assessment Programme uses to evaluate autobrake systems, which the group plans to begin rating in 2014.
The Institute awards as many as five points in the autobrake tests, based on how much the systems slow the vehicle to avoid hitting the inflatable target or lessen the severity of the impact. 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.
"We decided on 25 mph because development testing indicated that results at this speed were indicative of results at higher speeds â€” and because higher-speed tests would risk damaging the test vehicles," says David Zuby, IIHS chief research officer. "As such, we expect crash mitigation benefits at higher speeds as well."