Vehicle safety systems

Also known as Car safety systems, Passive vehicle safety, Occupant protection systems

Modern cars protect people in crashes through layers of design: crumple zones that deform in a controlled way, seat belts, airbags and independent crash testing. The IIHS reports estimates, citing NHTSA and Kahane (2015), that airbags and lap and shoulder belts together reduce the risk of death in frontal crashes by 61%. These figures come from models built on crash records rather than direct measurement.

CommercialDemonstratedReviewed 22 Oct 2026
AI illustration · Illustrative scene, not a photograph of the specific device or experiment.

In plain language

Modern cars are designed to protect people in a crash in several layers. The front and rear of the car are built to deform in a controlled way, absorbing energy as they crumple, while the middle section where people sit is designed to be the strongest part of the structure. In 1952 Béla Barényi patented this arrangement in Germany for Daimler-Benz. His patent does not use the words "crumple zone", but it describes the same idea.

The structure works together with seat belts, airbags and crash tests. Nils Bohlin's belt design, filed for Volvo in 1959, uses one sling to hold the chest and hips at the same time. Front airbags have been required in all new passenger vehicles in the United States since the 1999 model year. Independent programmes such as Euro NCAP publish crash tests and safety assessments of new cars, so that buyers can compare them.

Technical explanation

The crumple zone relies on controlled deformation. Barényi's German patent DE 854 157 was filed on 23 January 1951 and, according to Google Patents, published on 30 October 1952. Its claims describe strength that is greatest in the passenger compartment and decreases steadily or gradually towards both ends, with the end cells given lower impact resistance than the centre cell. The patent refers to predetermined breaking points at the ends and does not use the term 'crumple zone'.

Bohlin's belt uses a different geometry. Nils Ivar Bohlin's US patent 3,043,625 (filed 17 August 1959, issued 10 July 1962, assigned to Aktiebolaget Volvo) describes a chest strap and a hip strap that form one continuous sling. The chest strap attaches to a top mount on the body near shoulder height, and the hip strap attaches to a floor mount, so the belt holds the upper body diagonally and the hips across the seat.

Effectiveness is estimated from crash records rather than measured in controlled trials of people. The IIHS airbag page reports Kahane's (2015) estimates that front airbags reduce driver fatalities in frontal crashes by 29% and fatalities of front-seat passengers aged 13 and older by 32%. The same page reports an NHTSA estimate that an airbag and a lap and shoulder belt together reduce the risk of death in frontal crashes by 61%, compared with 50% for belts alone and 34% for airbags alone. Euro NCAP publishes crash tests of new cars. This profile did not open its protocol documents.

What the evidence says

Each statement is typed by the strength of its evidence and linked to the source that supports it.

Demonstrated Shown in a published experiment, test or shipping product.

Barényi's German patent DE 854 157, filed on 23 January 1951 for Daimler-Benz, describes a motor vehicle whose strength is greatest in the passenger compartment and decreases towards both ends, with the end cells given lower impact resistance than the centre cell.

Sources: [1] · Claims 1 and 3

Bohlin's US patent 3,043,625 describes a chest strap and a hip strap forming one continuous sling, with a top mount on the body and a floor mount, and it was filed on 17 August 1959 and issued on 10 July 1962.

Sources: [2] · Claim 1 and description

Since the 1999 model year, front airbags have been required in all new passenger vehicles in the United States.

Sources: [3] · Front airbags section

Euro NCAP describes itself as an independent organisation that is not a government agency and not part of the automotive industry. It says it has been active since 1996 and that its focus is on new cars available in the European market.

Sources: [4] · About Euro NCAP page

Reported, unverified Stated by a company or team but not independently confirmed.

In frontal crashes, the IIHS airbag page reports Kahane (2015) estimates that front airbags reduce driver fatalities by 29% and fatalities of front-seat passengers aged 13 and older by 32%. The same page reports an NHTSA estimate that an airbag with a lap and shoulder belt reduces the risk of death in frontal crashes by 61%, compared with 50% for belts alone and 34% for airbags alone.

Sources: [3] · Airbags page, summary of estimates · medium confidence

Limitations and open problems

  • Effectiveness figures are model-based estimates from crash data, attributed to Kahane (2015) on the IIHS page. They are not randomised trials, and this profile did not check the underlying analysis or its confidence intervals.
  • Frontal airbags can cause deaths when they inflate, especially in low-speed crashes. The IIHS page reports an NHTSA estimate of more than 290 such deaths between 1990 and 2008.
  • Faulty equipment can cause harm. IIHS reports that the Takata airbag recall, which began in 2015, covered an estimated 67 million vehicles by 2022 and has been tied to 23 confirmed deaths in the United States.

Timeline

  1. 30 Oct 1952German patent DE 854 157, filed by Béla Barényi for Daimler-Benz on 23 January 1951, is published. Its claims describe a passenger cell that is strongest in the passenger compartment and weaker towards both ends. Sources: [1]
  2. 17 Aug 1959The application for Nils Bohlin's US patent 3,043,625, a chest and hip safety belt sling assigned to Aktiebolaget Volvo, is filed. Sources: [2]
  3. 10 Jul 1962US patent 3,043,625 for Bohlin's chest and hip belt sling is issued. Sources: [2]
  4. 1996Euro NCAP describes itself on its own website as active since 1996, as an independent programme that is not a government agency and not part of the automotive industry. Sources: [4]
  5. 1999Front airbags are required in all new passenger vehicles in the United States from the 1999 model year, according to IIHS. Sources: [3]

Glossary

Crumple zone
A section at the front or rear of a car that is designed to deform in a controlled way during a crash, absorbing energy before it reaches the passengers.
Three-point seat belt
A belt with a shoulder strap and a lap strap joined into one sling, anchored at three points on the car body.
Airbag
An inflatable cushion that fills with gas within a fraction of a second when a crash sensor detects a severe enough impact.

Sources

  1. patent
    Kraftfahrzeug, insbesondere zur Beförderung von Personen (Motor vehicle, in particular for the transportation of people)
    Béla Barényi. Deutsches Patentamt (patent record via Google Patents); assignee Daimler-Benz AG, 30 Oct 1952. Accessed 22 Oct 2026.
  2. patent
    Safety belt
    Nils Ivar Bohlin. United States Patent and Trademark Office (patent record via Google Patents); assignee Aktiebolaget Volvo, 10 Jul 1962. Accessed 22 Oct 2026.
  3. other
    Airbags
    Becky Mueller. Insurance Institute for Highway Safety (IIHS), 2026. Accessed 22 Oct 2026.
  4. other
    About Euro NCAP: Who we are and what we do
    Euro NCAP, 2026. Accessed 22 Oct 2026.

Revision history

3 changes since this profile was created.

Changes on 22 Oct 2026
Published on owner instruction (car lineage tech tree, 2026-10-22)165371a
Sources and claims re-checked against originals409337d
Initial profile drafted from primary sourceseaac9eb