Mercedes-Benz can be credited with more technological firsts in the automotive industry than perhaps any other company, but it cannot lay claim to being the first automaker to offer a seatbelt airbag. Nor can it claim to be the second. Those two spots go to the Ford Explorer and Lexus LFA, both of which came out with seatbelt airbags in 2010.

Nevertheless, Mercedes isn't the sort of company to let the glory of being first get in the way of doing something worthwhile, and so its new Beltbag system for rear seat occupants will be coming to a luxury car near you soon. Our best guess is that the inflatable straps will debut on the redesigned S-Class that bows in the first half of next year, and then quickly proliferate throughout the brand's lineup.

Like the Ford system, Mercedes' Beltbag system is relegated to rear seats only and powered by charged gas that inflates the strap to nearly three times its normal width, thus increasing the surface area across which to distribute the impact forces of a crash. Unlike the Ford system, Mercedes says only a frontal impact will trigger its belts to inflate, whereas the Explorer's inflatable bags are triggered by both frontal and side impacts.
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Stuttgart. The Beltbag, one of the highlights from the ESF 2009 Experimental Safety Vehicle, is due to go into production in a luxury-class model from Mercedes-Benz. The inflatable seat-belt strap is able to reduce the risk of injury to passengers in the rear in a head-on collision by lessening the strain placed on the ribcage.

Should the crash sensors detect a severe frontal impact, the airbag control unit will trigger deployment and inflation of the Beltbag. A gas generator then inflates the multi-layered belt strap with Velcro seams to nearly three times its normal width. The resulting larger surface area is able to better distribute the force acting on the seat occupant, thereby reducing the risk of injury.
The Beltbag can be used in exactly the same way as a conventional seat belt. The belt strap's design is different from that of the standard belt though, and received top marks in practical trials for being extremely comfortable to wear and for its extra-soft belt strap edge.

"Mercedes-Benz is pursuing its safety initiative in the rear of vehicles with the Beltbag," comments Prof. Dr.-Ing. Rodolfo Schöneburg, Head of Passive Safety and Vehicle Functions at Mercedes-Benz Cars. "After all, the excellent standard of safety offered by Mercedes-Benz doesn't just apply to all model series, but to all seats, too."

Just like the active seat-belt buckle recently presented by Mercedes-Benz that is likewise earmarked for inclusion in a luxury model, the Beltbag was developed with a particular view toward new markets. There, the occupancy rate in the rear is as much as 30 percent, making it much higher than in Europe. By introducing the Beltbag, Mercedes-Benz is further expanding the safety system for passengers in the rear – in contrast to many other manufacturers, seat belts in the second row of Mercedes-Benz models already come equipped with belt tensioners and belt force limiters. It is not planned to introduce the Beltbag for the front occupants, as airbags are already included in the front on all models as a supplementary restraint system.

Because dummy measurement technology is not capable of quantifying the benefits resulting from a wider belt strap, such as the lower force exerted on occupants, the safety experts at Mercedes have also been working intensely with virtual human models, as such computer-generated models make it possible to obtain detailed findings on the biomechanical strain during a collision.