Mercedes-Benz’ Safety Symphony

The popularity of electric passenger cars being adopted in the past two to three years globally has been unprecedented. A total of 14 percent of all new cars sold were electric in 2022, up from approximately 9 percent in 2021 and less than 5 percent in 2020.

Issues like range anxiety, battery costs and safety rank on the top of the list for OEMs to work on and the fast pace of technologies that are being introduced is taking care of that. Progressive carmakers like Mercedes-Benz are going above and beyond not only the legal safety requirements but also those of the mandated safety ratings for its EVs.

According to Euro NCAP norms, it stipulates a frontal impact test using a 1,400 kg trolley with an aluminium honeycomb barrier replicating the front of another vehicle. A test vehicle and the trolley are made to collide at a speed of 50 km/h in the lab.

While keeping all this in mind, crash test engineers at the Group's Technology Centre for Vehicle Safety in Sindelfingen, Germany, used two actual vehicles – an EQA and an EQS SUV to perform the test. Both these EVs are heavier than the prescribed test mules and both models were crashed head-on at 56 km/h. This aspect meant that the overall crash energy was considerably higher than prescribed and the vehicles' extensive deformation following the collision may seem alarming to a non-expert.

For the Mercedes-Benz engineers, however, it had a different meaning. They were happy to note that despite the crash, the EVs were able to effectively absorb the energy quite well through the process of deformation while ensuring that passenger safety cell remained intact and that the doors could still be opened. As a precaution, the high-voltage system in the EQA and the EQS SUV switched off automatically during the collision.

Real time versus simulated crash tests

Mercedes-Benz says that the test scenario involving crash testing the EVs at speed of 56 km/h with 50 percent frontal overlap corresponds to a type of accident common on rural roads, for example during a failed overtaking manoeuvre. The speed selected for the test considers that in a real-life accident, drivers would still try to avoid the collision by braking hard before an imminent crash situation.

Involving advanced crash dummies

For the crash test, both the EQA and the EQS SUV had two adult dummies – a total of three females and one male. Analysis of the up to 150 measuring points per dummy indicate a low risk of serious to fatal injury. This means that the defined crumple zones and advanced restraint systems in both vehicles offer very good protection potential for the occupants in a crash of this severity. All safety equipment, such as airbags and belt tensioners with belt force limiters, worked as intended. The crash test thus confirmed the results that the engineers had previously calculated in numerous computer simulations.

Female dummies in the driver's seat

Interestingly, another aspect of the crash test was the type of dummy that was being used. According to the technical classification of the driver seat dummies of both vehicles, they were of the Hybrid III 5th Percentile Female type. In fact, they represent the female dummy currently used in the automotive industry for frontal collision tests.

The dummy corresponds to a woman of approximately 1.5-min height and weight around 49 kgs. According to the underlying statistics, only five percent of women worldwide are smaller or lighter, and for many years, Mercedes-Benz has used frontal crash tests with fifth percentile female dummies in the front seat to design its protection systems for the widest possible range of customers. Ratings by consumer protection associations as well as various legal requirements worldwide now include specifications for testing with fifth percentile female dummies. Another fifth percentile female was a passenger in the EQA. In the passenger seat of the EQS SUV was a Hybrid III 50th Percentile dummy, that represents a 78 kg male of average height.

High-voltage safety

Mercedes-Benz claims that it has developed a multi-stage high-voltage protection concept for its EVs. The wiring system has eight key elements to ensure the safety of the battery and all components where the current is above 60 volts. Examples include separate positive and negative wiring and a self-monitoring high-voltage system that automatically switches off in the event of a serious collision.

In a fraction of a second

For safety design engineers, what really matters are the events that take place this fraction of a second during an accident. Their job and expertise will ensure that all safety systems work together seamlessly at just the right time to protect life as best as possible. For greater awareness, the new campaign film on the brand’s EV safety is aptly titled ‘Safety Symphony.’ In an unprecedented way, it visualises how the different safety systems work together.

M-B Technology Centre for Vehicle Safety

Touted as one of the most modern facilities in the automotive world since 2016, it has been conducting crash tests at the new Group-owned Technology Centre for Vehicle Safety in Sindelfingen, Germany. The test centre is one of the largest and most modern of its kind in the world. It has three highly flexible crash lanes leading into a large, support-free area measuring over 86,111 square feet. At this facility, Mercedes-Benz conducts up to 900 crash tests and 1,700 sled tests every year.

The luxury car brand has over six decades of experience with crash tests. Along with analysis by the Group's Accident Research unit, this experience forms the basis for the real-life safety philosophy. Founded in 1969, the Accident Research unit analyses accidents involving modern Mercedes-Benz cars.

This article was first published in Autocar Professional's December 15, 2023 issue.