In 1951, Mercedes-Benz applied for a patent for the world’s first safety body with a stiff passenger safety cell and defined crumple zones. The design went into production in 1959.

Cars today are generally much safer than earlier models, as they have better safety features and devices. While the effectiveness of certain features like seat belts or air bags can be more easily proven, the same cannot be said about crumple zones because there’s no way to prove their usefulness except when one is involved in an accident – something you wouldn’t want.

How a crumple zone works

The crumple zone is an area of a vehicle that is designed to deform and compress in a collision, in order to absorb the energy from an impact. Another purpose of the crumple zone is to increase the amount of time from when the car hits an object to when it comes to a complete stop.

By increasing the time it takes for the car to stop, the force is spread over a longer period of time and thus its impact is minimised before it reaches the vehicle’s occupants. In other words, the crumple zone tries to use up as much force as possible so that the impact doesn’t get transmitted to the occupants. This in turn ensures that the occupants are better protected against injury.

In a crash, intense kinetic forces are at work. The amount of force generated is based on the acceleration (change in speed over time) and mass of the car; and the acceleration and mass of whatever it hits (Force = Mass x Acceleration).

In a collision, slowing down the acceleration by even a few tenths of a second can create a drastic reduction in the force involved. Supposing the crumple zone increases the amount of time taken for the car to stop from 0.01 seconds to 0.2 seconds, the resultant force that the passenger is subjected to is reduced by 20 times.

Where’s the crumple zone?

A common misconception about crumple zones is that they reduce safety by allowing the vehicle’s body to collapse, crushing the occupants. But in fact, modern vehicles with crumple zones provide, on average, better protection for their occupants in high-speed crash tests than older cars.

Crumple zones are located at the front and back of the main body of the car, and can be compacted within the space of the engine compartment or boot. The entire car cannot be a crumple zone. Certain parts of a car must be rigid and resistant to deforming, such as the passenger compartment and the engine.

The passenger compartment needs a rigid, strong frame to withstand being penetrated by external objects or other parts of the car during an accident; and it has to hold together so the occupants don’t get thrown out. Seat belts and air bags are deployed concurrently to protect the occupants.