I have read some studies about frontal airbags and their minimal effects in most collisions. I don't remember where I read them though. Im sure you could find some information in the search engines if the topic interests you.

Logic however would allow one to draw some conclusions. Most Minor accidents don't result in passenger compartment deformation especially in a Mercedes (I believe my 126 was designed to sustain a 50mph collision with a solid barrier and still be able to operate the doors). If the passengers are both wearing their seatbelts what exactly are they going to collide with and be injured from in an accident? Airbags are great for extreme accidents when the dash starts to move into the passengers compartment, however in such a solid car the speeds required to deform the cabin are much higher than we "normally" have here in the states.

Don't get me wrong. I like having the Airbags in my 140, however in an older car without side airbags they provide minimal benefit. My 126 does not have airbags and I am glad they are not there so I don't have to worry about 24 year old first generation technology accidently deploying in my face. I don't feel any less safe in the 126 because it has seatbelts and a "similar" energy absorbing front end. The airbags I think are the most important are the side airbag because doors are much thinner than the entire front clip of a car and seatbelts only work front to back rather than side to side.

In smaller subcompact cars even a front airbag provides a lot of benefit because it takes less energy to deform the passenger compartment of these cars.

A lot of the saftey ratings for some of the newer cars are somewhat misleading. Smaller lighter cars have less mass and therefore have less overall crash energy with a solid barrier. In the "real world" you have the mass and crash energy of more than one vehicle in sometimes more than one direction. In full size S class vs Honda Civic Im glad Im the guy thats driving the S class.