It has always held true in physics, the more a vehicle weighs, the better off you are.
While the newer vehicles are beefy, it is not because contemporary design forces massive amounts of high strength steel/aluminum/titanium etc into the safety cage. It is because of all the electronic boxes and such.
After the W140, Benzes stopped being as "tanklike". The W140 always felt like a rock to me, and pretty close to the W126 in solidity.
That being said, my base model 3.0 liter S-Class diesel weighs ~4200 lbs with no spare tire, or luggage, a full tank of fuel, and a 150 lb driver (me).
No options, no ASR, No COMAND, no microprocessors, no heavy duty differential, no six piston calipers, only one battery, not two or three, not enough wiring to span the globe (big penalty), no electronic engine computers, no nothing.
Just a lithe, rigid body with less crumple capacity than the newer versions. W140's seem to have crumple zones in the doors. W126's have 1" steel beams, DOT certified, running through the doors.
Sorry, the W126 is the last super solid Benz.