The 850 was know for many "issues"

1) AC Evaporator was Aluminum/Plastic JUNK and replacement was harder than on a 320E! Minimum 12 hours labor!
2) Engine Mounts and Upper Strut Bearing wear out in short time. Replacement of the Upper Strut is easy but Engine Mounts are $$$
3) Transmissions-850 AutoBox is known as AW-50 and is a POS! Made by Toyota and undersized. Do a Power Launch and it can Grenade.
4) Struts-Front end eats 'em. Rears are so so.
5) Crash Safety-It AIN'T a 240! Occupant Death Rates are MUCH Higher than 740/940//240 series. Wagons have been known to bend right behind the drivers seat in a head on collision, compromising the "Safety Cage" design.
6) Early version of White Block in line 5 cyl motor copied from AUDI design. Issues with Main Bearings and Cooling Passages. Similar issues to 960 Twin Cam 6. Bad Castings led to "porious block" syndrome and failure of cooling system integrity. Parts are not cheap