A highway safety group's new crash test that emulates offset head-on collisions could prompt automakers to make front-end modifications that add to vehicle weight and cost.
Manufacturers such as Honda and Mercedes-Benz also are concerned about the side effects of such changes, which could adversely affect fuel efficiency and handling.
On Tuesday, the nonprofit Insurance Institute for Highway Safety plans to release initial results of its new frontal small overlap test, which measures how well vehicles hold up during 40-mph frontal collisions where there is 25 percent overlap with a deformable barrier. The current moderate overlap test measures damage from 40 percent overlap crashes.
Institute President Adrian Lund said one of the main problems with small overlap crashes is that the typical energy-absorbing structures on the front middle 50 percent of vehicles are never engaged.
Instead, the wheel is the first to receive the blunt force during small overlap incidents, which account for 25 percent of the 10,000 fatal frontal accidents that occur each year, according to the institute.
Vehicles must meet regulatory requirements based on the moderate overlap test from the National Highway Traffic Safety Administration and the European New Car Assessment Program.
Insurance Institute for Highway Safety standards aren't legal requirements.
In the current study, the institute tracked 11 mid-sized luxury vehicles, including the 2012 Mercedes-Benz C class and BMW 3 series.
Lund said auto companies likely will start putting structures on the front end that absorb impacts before the wheel does, while strengthening the occupant compartments so they don't collapse when the wheel is contacted and pushed back into the foot well.
But these changes could increase costs.
"There's no free lunch. Yes, it's going to cost some money to change the vehicles," Lund said in an interview. "Probably, in the early designs, it may add some additional weight to vehicles as well. We suspect that, over time, automakers will be designing from scratch to do well in this and then they will be more efficient about how they build it."
Honda expressed concerns because the alterations could affect handling, ride comfort and fuel economy.
Still, the company said in a statement that it will begin making "structural enhancements" on upcoming vehicles this year with the second generation of its Advanced Compatibility Engineering body structure.
The alteration to the front frame structures "provides further enhanced frontal crash energy management through a wider range of offset and oblique crashes," the company said.
Meanwhile, Mercedes-Benz said in a statement that the test re-creates an "unusually severe and correspondingly uncommon accident scenario" that put the C class at a disadvantage.
Mercedes added that the "real-world kinematics of vehicles involved in this type of crash are very different from the construct of the IIHS test."
The institute is aware of Mercedes' concerns, but Lund said data indicate this is a significant issue.
Said Lund: "They wish they had more time to get ready for this test, but I think that most automakers recognize that the real-world data is showing that this is a real problem." c
