Well, I've owned a few 190E's.
The 190E is a pretty durable little car, and the M102 four cylinder versions are tough, but not quick. The 2.6 is much quicker, but tougher to work on as the engine bay is quite crowded.
By 1993, the 190E, all versions, were pretty much sorted out. They are the best of the breed, by far.
On the 2.6L M103 versions you should watch out for the occasional leaking head gasket. Not the problem that the M104 is, but still should be checked. Valve seals tend to age before other top end components, but are not too tough to replace. The front engine gasket will also leak a bit, but nothing to get concerned over.
Both cars have four speed auto-boxes that usually last at least 150,000 miles with regular fluid/filter changes.
Plastic rads break just like any other car, and original or old rads should be suspect. Look for MB coolant and regular changes.
I drove all my 190E's to well over 300,000 kilometers without any major problems. (190K-miles) When I worked in sales I bought lower mileage 190E 2.3 cars and drove them and drove them and drove them and then sold them with high odo readings and having spent next to nothing on repairs.