The First Airbag: GM ACRS vs. Mercedes SRS

It's a bone of contention: Who invented the airbag, GM or Mercedes?

GM's ACRS, which launched in December 1973 on certain 1974 model General Motors full size cars, was the first airbag system put in cars that were available to the general public.

One of the impetuses for developing ACRS was the "ignition interlock" rule, a NHTSA mandate that required all cars made beginning in the 1974 model year to not allow the vehicle to start unless the driver's seat belt was fastened, unless the car was equipped with a "passive restraint", a restraint system that requires no action from the occupants. ACRS allowed so-equipped vehicles to not be equipped with the interlocks, and they weren't.

ACRS was a dual airbag system; a driver-only variant was never offered. Surprisingly, the airbags were "dual stage", meaning that they could fire at two different levels of force, depending on crash severity. (This feature would not reappear in any car until about 25 years later, and wasn't adopted on all US-market cars until 2007. Of course, today's dual stage airbags take far more variables into account, such as seat position and occupant weight) 

Not surprisingly, there were some differences between it and modern airbag systems. ACRS was marketed as a replacement for shoulder belts, and ACRS-equipped vehicles were equipped only with lap belts. The airbags were larger and more aggressive than modern systems; in fact, the passenger airbag extended all the way from the right edge of the steering wheel to the passenger door, and was deep enough to go all the way back to the unoccupied seat (meaning it would hit a passenger several inches before full inflation). The driver airbag didn't have a vent hole, instead venting indirectly through the steering column, in effect allowing it to remain partially inflated for a few seconds.

Mercedes' SRS was introduced in December 1980, initially offered only in Europe (it would make it to the USA in 1983 for the 1984 model year). It was the first airbag system to operate on the same principle all modern airbags do; as a Supplemental Restraint System, supplementing the primary restraint system, the 3-point seat belt. The early SRS system featured a driver airbag and pre-tensioners for both front seat belts; a passenger airbag was offered on some Mercedes models beginning in 1988.

All subsequent airbags have been based on the SRS ideal, and many airbags still say "SRS Airbag" on them (including the airbags in my 2011 Honda Accord).

Beginning in the mid-1980s, other automakers introduced airbags based on the SRS ideal, although seat belt pretensioners wouldn't become standard on most cars until the late 1990s. General Motors themselves introduced their first modern airbag system in 1987 as an optional feature on the 1988 Oldsmobile Delta 88; their early systems used the abbreviation "SIR" (Supplemental Inflatable Restraint). In 1996, the last passenger vehicle not equipped with airbags, the Mitsubishi Mighty Max pickup truck, was discontinued; since then, every vehicle sold in the USA has had airbags based on the SRS ideal. By the end of the 1990s, nearly every new vehicle sold in Europe had an airbag, and this was the case in Australia by the early 2000s.


Here's a Buick dealer training film from 1974, explaining the ACRS system:

Here's a Mercedes commercial from January 1986 for the SRS system:




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