Frontal Impact

In the event of a frontal impact, the force is distributed as follows: The force is passed from the aluminum-section bumper crossmembers via two deformation elements to the engine subframe members. From there, the forces are channeled into the sills and the transmission tunnel ("Y" structure). The transmission tunnel is reinforced by 4 tunnel side members.

Each of the sills is reinforced on the inside by 4 bulkheads. This also helps to prevent deformation of the passenger compartment.

Fig 1: Identifying Body Structure

Courtesy of BMW OF NORTH AMERICA, INC.