Both BMW and Daimler are in for a very rude shock if they don't upgrade the quality of the parts used and downgrade the unnecessary complexity of their "expensive" cars. They both are running on past reputation for performance and reliability, and neither make adequate automobiles any more.
BMW 740 series cars eat money like nothing you've seen before (new parts sometimes arrive broken just like the one being replaced!) and cost the earth -- just watch the owner of one a couple years old trying to lock the doors with the key (since they won't pay $1500 to replace the servo for the keyless entry), and what do yo do when the door closer motor quits and and you can no longer close the door (another grand). Or you can't use the windows or sunroof because the "convinenice relay" box blew (again) for $2500.
The W140s are well known for blown ignition boxes ($4000), blown injection boxes ($4000) and blow climate controls ($2000), usually two or three time by the end of the lease or warrenty.
Doors sound like a Neon, build quality is trash, and I've heard the MLs are built on the American operating plan -- if most the the parts are still on it when it gets to the dealer, it's the customer's problem. Quality control consists of getting the vehicles out the door fast, nothing else.
Sooner or later the people who buy these new won't pay for a car, at that price, that they cannot give away after three years! At that point, MB will either wake up or go out of the automobile business.
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!