All I can relate to you is my own experience with buying a '96 S500 Coupe just over a year ago.

I disagree with ehmand on a couple of points... first, the wiring harness in the 96/97 is different than the '95s and earlier. I'm not aware of any harness issues in the 96/97. I've unwrapped my harness in places and the insulation looks good and is nice and pliable. No oil problems around the heads either. Again, if you'll do some research you'll find the 96/97 S500 has a different engine number than the earlier cars... i.e. different motor by part number.
My W140 Coupe does not eat tires or brakes compared to any other car I've had in the weight/size category. I put new tires on it when I bought it... have driven just over 20K miles.. tires are about half gone... and they are W rated... so they are somewhat soft. I'll drive em another 10-15K and swap them out for another set.

Bought mine with 75K on the clock, paid 22K for it January 2003. (just over a year ago). Frequently drive it to work when the weather is good... 5 hours total commute... about 140 miles round trip in mixed city/highway... averages just under 20 miles per gallon. I wouldn't call that a gas guzzler. Wish my plain Jane Ford pickup did so well.

Only part I HAD to replace in the last year was the left O2 sensor forward of the cat. Have replaced some other stuff as preventative maintenance. There are a few things that still need attention like rear head rests that make noise when lowering, but just an annoyance at best.

Maybe I'll change my mind tomorrow, but so far the reported "bad things" I've been assured will happen haven't happened. Car has performed flawlessly and you know how they drive.

All cars have some issues... the BMW will have its own set. Here in Washington DC, there's a BMW of every type commonly seen. In the last 20K, I've only seen one other W140 Coupe.
Hope this helps.

__________________
KenP

1996 S500 W140 Coupe