The IIHS independent frontal offset and side impact tests for Mustang show room for improvement.
06-04-07: The Insurance Institute for Highway Safety (IIHS) recently released findings and ratings for crash tests on the 2005-2007 Ford Mustang Convertible. The resulting ratings, which are based on a uniform system explained further on in this article gave the Mustang Convertible an “Acceptable” rating for the “frontal offset” crash test and a “Good” rating for side the impact crash test.
The Institute conducted 2 frontal tests of the Mustang. In the first test, the driver door partially opened late in the crash. Even though this didn't significantly affect the driver dummy's movement during the impact, doors shouldn't open because in some crashes this could lead to partial or complete ejection of occupants.
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Ford engineers found that the window glass in the down position pushed on the door latch during the crash. Structure was added in the door to prevent the glass from contacting the latch mechanism, and then the engineers asked the Institute to test the Mustang again. In the second test with the change, the door remained closed.
The modification goes into production beginning with 2007 models manufactured after May 2007 to reduce the likelihood of door opening in frontal offset crashes. Information about when a specific vehicle was manufactured is on the certification label typically affixed to the car on or near the driver door. The two cars are rated separately for the frontal offset crash, but the overall rating for each is Acceptable.
Restraints/dummy kinematics: Dummy movement was reasonably well controlled. The dummy's head hit the A-pillar, which bent downward and inward during the crash. This is one of the unfortunate drawbacks of convertibles. Without a permanent roof structure to support the A-Pillar, they often tend to move straight in at the heads of occupants.
Injury measures: Measures taken from the neck and chest indicate low risk of injuries to these body regions in a crash of this severity. A high head acceleration occurred when the dummy's head hit the steering wheel through the airbag, indicating that head injuries would be possible. Forces on the right tibia indicate that lower leg injuries would also be possible. Head acceleration from the A-pillar hit was low.
The Mustang is rated acceptable instead of good overall because the structure isn't good, and the dummy's head bottomed out the airbag. The resulting head acceleration was high. The head was struck by the windshield pillar.
For side impact safety, beginning with 2007 models manufactured after January 2007, the optional side airbags were modified to improve occupant protection in side impact crashes. In this test the Mustang fared much better with a “Good” rating.
Injury measures: Driver — Measures taken from the dummy indicate that rib fractures would be possible in a crash of this severity. The risk of significant injuries to other body regions is low.
Injury measures: Rear passenger — Measures taken from the dummy indicate a low risk of any significant injuries in a crash of this severity.
Head protection: Driver — The dummy's head was protected from being hit by any hard structures, including the intruding barrier, by a side airbag that deployed from the seat.
Head protection: Rear passenger — The dummy's head was hit by the interior side trim and convertible boot (cover for the folded roof). These impacts did not produce high head injury measures, but the head protection is inadequate.
Absence of roof is inherent disadvantage. High-speed crashes are violent events, and the roof of a hardtop helps to keep people's heads and arms from flailing outside the vehicle. Roofs also provide protection if a vehicle rolls over. Data from real-world crashes indicate that the overall risk of death isn't higher in a convertible, but this doesn't mean there aren't any safety disadvantages.
The absence of a roof makes it a challenge to design a convertible for safety. The roof helps to maintain the rigidity of the structure around the occupant compartment and keep the compartment intact in a serious crash. The main structures of convertibles have to be strengthened to compensate for the support that's lost in removing the roof. Of course, without a top all bets are off if you're not using a safety belt. Good test results don't mean convertibles are as protective as comparable hardtop cars.
How vehicles are evaluated: The Institute's frontal crashworthiness evaluations are based on results of 40 mph frontal offset crash tests. Each vehicle's overall evaluation is based on measurements of intrusion into the occupant compartment, injury measures recorded on a Hybrid III dummy in the driver seat, and analysis of slow-motion film to assess how well the restraint system controlled dummy movement during the test.
Side evaluations are based on performance in a crash test in which the side of a vehicle is struck by a barrier moving at 31 mph. The barrier represents the front end of a pickup or SUV. Ratings reflect injury measures recorded on 2 instrumented SID-IIs dummies, assessment of head protection countermeasures, and the vehicle's structural performance during the impact. Injury measures obtained from the 2 dummies, one in the driver seat and the other in the back seat behind the driver, are used to determine the likelihood that a driver and/or passenger in a similar real-world crash would sustain serious injury to various parts of the body. The movements and contacts of the dummies' heads during the test also are evaluated. Structural performance is based on measurements indicating the amount of B-pillar intrusion into the occupant compartment.
