Boy did you pick a bad time to ask that question. My plans today were to write my article for next months "Import Car" magazine about MB suspension/alignment issues. I had planned on avoiding that issue (spreader bars).
I have checked and MB does show it used on 126, 124, 201, and 210 models (I have verified this in the WIS this morning. It undoubtably is the same for others. I can tell you that I have been doing MB alignments since 1973 and even when I was at the dealer, we didn't use or have a spreader bar. They may have one now but I can tell you that I have done thousands of MB alignments and have paid close attention to wear patterns that could be attributed to technique or equipment calibration and I do not have any history of inside tire wear which spreader omission would creat.
I do check the play of all front ends that I do align and would fix any that spread more than the min-max tolerance given: 2-3mm.
The latest tool that is used for 98- specs is used for incorporating ride height into the numbers. It is my contention that a proper alinment tech will take tire wear, driving performance, load/ride height and spreadability into consideration by the techniques available to him. BMW has prescribed weights that must be placed in various places about the car, MB wants it unloade but full of gas. I use my 280lbs to load the car and evaluate changes in camber and toe. its part of my technique that may not be used by everyone (bg).
The car when done should follow a flat straight road endlessly with the steering wheel perfectly straight. everything else is to be addressed. And especially with the poorly adjustable cars (everything since 202) tires are usually the problem. Always rotate the front tires side to side when pulling is a problem. If this affects the pull I would either get new tires or try switching them to the rear. I'm not sure MB would say this but there are service bulletins from BMW and Volvo (whose modles have always lacked adjustability) about using this as a first diagnostic step.
Bosch Master, ASE Master, L1
33 years MB technician