This report is a statistical evaluation of the fatality- and injury-reducing effectiveness of the energy-absorbing materials in vehicles without head-protection air bags. (NHTSA previously evaluated the effectiveness of head-protection air bags in 2007.2) In one sense, this report evaluates a specific technological approach (energy-absorbing materials without air bags) that is already phasing out. But the energy-absorbing materials, themselves, will not be phasing out; they will continue to appear in new vehicles to protect occupants in crashes where the air bags do not deploy or perhaps at locations not covered by the air bags. More generally, the report investigates whether a technology demonstrated to have reduced HIC measured on headforms in laboratory testing is likewise effective in reducing the head injuries of people in crashes.