Even for people in the car, some older car designs put the drivers legs under the engine block. In a head on collision at speed, the legs were the crumple zone (meanwhile the steering column was being pushed through your torso).

edit: also recently people noticed that high 'trucks' would simply miss the crumple zones in the car they were crashing into

> Another problem is "impact incompatibility" where the "hard points" of the ends of chassis rails of SUVs are higher than the "hard points" of cars, causing the SUV to "override" the engine compartment of the car.[18] In order to tackle this problem, more recent SUV/off-roaders incorporate structures below the front bumper designed to engage lower-height car crumple zones