FWIW, a few years ago Road and Track did an owner's survey for the 96 through 00 E-Class and the most common complaint was frequent need for alignment. We've got a 99 4matic that we bought used (30K miles) last year. The steering generally felt fine and didn't pull, but usually required a few degrees of right correction, even when the crown of the road should have required a left correction. An alignment at the dealer when I put on new Michelins took care of that plus improved the self-centering feel when accelerating through a turn. That was 6000 miles ago and it's been fine ever since. I'm glad I had the alignment done.
99 E 320 S4matic
02 ML 320