Each year in the U.S., it is estimated that 4000 persons are killed and another 9300 sustain serious head injury due to impacts with vehicle upper interior structures. The safety performance of passenger vehicles in occupant head impacts with the upper interior is examined in this paper. The upper interior is defined as the A/B/C-pillars, the side roof rails, the front header rail, and the rear header rail. The results of a recent NHTSA fleet characterization effort involving over 220 free motion headform (FMH) impact tests on fourteen passenger cars, light trucks, and minivans are presented in this paper. The effects of variations in impact angle, impact location, and contact velocity on FMH responses are explored in this test series. Localized hard spots and protrusions (e.g. motorized seat belt tracks) were identified and tested to determine design-specific head impact hazards. The conclusions are that head impact injury potential is a strong function of vehicle design, and that upper interior head impact protection varies widely from vehicle to vehicle.