Wiring harness, evap () and tranny are always discussed. Maybe with the low mileage you're in good tranny shape.
Those are generic W-140 issues. Others will chime in on other issues with that chassis and with the S500 specific things...

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John