"I briefly owned a 97 528. Nice car. Sold it to my neighbour, and she loves it."
That about says it all for me, "she loves it".
Comparing a BMW 528 to a MB E420 is like comparing apples and oranges. 528 vs. E320 or the 540 vs. E420 would be like comparing apples to apples. I test drove a 528 and it just didn't have the get up and go like I wanted. I've maintained BMW's in the past and I'll guarentee you that you won't find tech support like this Forum, and I think that the prices for maintainance parts are higher for BMW (beleive it or not). I've had some priced on BMW parts that make me scratch my head and wonder if it was worth it, not so with MB yet (knock on wood). I can't say enough about this Forum, it is a big reason that I'm not looking for a 540. I'm currently drooling over a 1997 E420 Sport...
1998 BMW 540i Sport
1989 BMW M3
1979 Triumph TR7 (1st car)
1986 BMW 735i (Sold)
1980 BMW 320i (Sold)