The weight difference between an early W124 300E and the W201 190E 2.6 is not that much. The car is a little bigger (about a foot) but not enough to make a huge difference in crash performance.
As an aside, the A-Class and the C-Class do as well in crash testing as an S-Class.
The lust for "safe mass" is one thing that has lead to SUV-mania in the first place. Hopefully this lunacy is over, and we can get back to driving real cars. BTW, engineering is everything. The GM, Dodge and Ford full size trucks are crap in crashes. They may have weight, but they are made of cheap materials and the passenger spaces fold like cardboard boxes. Ironic that so many people buy them for safety, and they are terribly unsafe.
1998 C230 "Black Betty"