Mercedes-Benz safety body with crumple zones

What it is

The safety body is a car body design in which a rigid passenger compartment is surrounded by deformable front and rear sections, the crumple zones. The idea was patented by the Mercedes-Benz engineer Béla Barényi under German patent No. 854 157, dated 28 February 1952. It entered series production in 1959 in the Mercedes-Benz W 111 saloon, nicknamed the Fintail.

How it works

In a collision, a car must dissipate a large amount of kinetic energy. If the whole structure is rigid, that energy is passed to the occupants as violent deceleration. Barényi's insight was to separate the car into zones with different tasks. The front and rear are designed to fold up in a controlled way, absorbing energy over a longer distance and reducing the peak forces. The passenger cell, by contrast, is made as stiff as possible so that it keeps its shape and protects the space around the occupants.

Why it stands out

The principle sounds obvious now, but it overturned the older belief that a stronger, more rigid car was always safer. It became the basis of passive safety in virtually every modern passenger car. Mercedes-Benz also began systematic crash tests with dummies in 1959 to validate the concept, and continued to introduce safety features in its S-Class, including the driver airbag in 1981. Barényi is often called the father of passive safety.

Where you meet it

Every time you sit in a modern car, you benefit from the idea. Crash test programmes such as Euro NCAP assess how well crumple zones and passenger cells work together, and the concept has been extended to side impacts, pedestrian protection and electric cars with large battery packs.