This car has the early version of the M104 engine which uses an updated fuel injection system from the earlier M103 cars (CIS E). Displacement is still 3.0 and not 3.2 like the 1993 and later straight 6s in the W124s. It is a 24 valve unit with variable valve timing. My first check would be to ensure that the head gasket and various other engine gaskets are not leaking any oil or coolant. If they are, the lower block and undercarriage will likely have some saturation of oil. I would also check the coolant to make sure that no oil has entered into it. Head gaskets were a problem on these engines and if it has not already failed it will only be a matter of time before they do. I'm not absolutely positive if the wiring harness problem affected the early M104s but a good PPI should reveal any problems with it. I would check ALL the electrics to make sure they work. Also check to see if the A/C works as it should as repairs are expensive, most notably is the evaporator. Make sure the heater and fan blow the according amount of air to the right places. The fan speed should increase in the max cold or hot positions. If you can, drive the car on a hot day and bring a thermometer so you can measure the vent temperatures with the A/C on. Check to make sure the car starts and idles well. Pay attention for any delays, hesitations or uneveness when starting or driving. With such low mileage, many of the rubber parts for the engine and suspension can dry out and crack. When you get the car inspected, have the rubber suspension and engine components examined closely. Check all the fluids including the transmission level and color. Also, note the performance of the transmission by ensuring that it engages without delay and does not slip or shift hard. Make sure the coolant is not green and also look at the color of the brake fluid and note its color. Take the oil filler cap off and check the underside for milkiness or excessive sludge. Check over the body and undercarriage thoroughly, looking for paint and body defects as well as rust. The seatbelt extenders should come on when you turn the ignition on and retract after 30 seconds or when you buckle the seat belt or open a door. They should come back out after the door has closed provided the seatbelt is not engaged in the buckle. The seat backs should lock into place if the engine is running and doors closed. They are unlocked with the engine off or the door open. Check the rubber seals around the door and glass where the back window meets the front. These former items are coupe/cabriolet particulars. A pre purchase inspection by a reputable independent specialist is a must as are service records. Let us know how the car checks out!