What is crash compatibility and how is it addressed in vehicle design?

Crash compatibility ensures vehicles of different sizes protect occupants in collisions with each other. Key aspects include geometric compatibility (aligning energy-absorbing structures vertically - typically 400-500mm from ground), stiffness compatibility (not having one vehicle too stiff causing other to absorb all energy), and mass compatibility (managing higher deceleration in lighter vehicle). Regulations like EC frontal impact include MPDB (mobile progressive deformable barrier) that penalizes aggressive structures. Design balances self-protection with partner protection.