Rick, I own a 1989 300TE with the M103 engine. I bought it used for my daughter's first car (she is now on her second Benz
).
The M103 engine is nearly indestructible. The 300TE now has over 225K miles on the clock and it runs like a fine Swiss watch. It does not leak oil (heck it barely uses any oil between oil changes, less than a quart every 3K miles), it runs smoothly and it has been extremely reliable. Until my son starts to drive it, the 300TE pulls duty as the all-around hauler. I have moved more furniture and boxes in that wagon than in any other vehicle I'vbe owned.
The 300TE developed an engine cut-out problem, but once it was diagnoesed and fixed (it was a defective Hall Effect Sensor) the car has not had any problems.
Right after she got her driver's license my daugher was involved in a collission where she rear ended a truck. In spite of heavy front end damage (fixed and paid for by the insurance company) my daughter did not even get a scratch. I would vouch for the safety of these cars. And if you watch the YouTube videos, where a British TV crews tries to destroy a 300TE (all to no avail) you too would know that these cars are as solid as they can get.
The M103 engine does not have a headgasket problem. That came much later. The M103 engine also does not have a wiring harness problem. This happened much later, when the Germans began using a different kind of material to wrap wires.
If you have not bought the car yet, you should seriously consdier getting it. You will be glad you did and your daughter will be very safe--plus she will drive to school in the kind of style that no Japanese car will ever provide.
Of course, I am biased. If you lok at my signature, you will see that I am a very big fan of the W124 class.
Regards.
(NOTE: After reading your post I realized that you are talking about a 1993 320E. I have no experience with the engines on those cars. But my other comments still apply).