When I purchased my 300D, the previous owner had put 112,000 miles on it. I took it to a Mercedes-Benz dealership in Memphis, TN to have the car brought up to full operating reliability. A number of repairs and replacement parts were needed, with the final bill exceeding $7500. While the car's exterior and interior were generally in immaculate condition, periodic maintenance had evidently not been regularly done. The following maintenance was performed by the shop:
The radiator was replaced.
The water pump was replaced.
The thermostat was replaced.
Belts and hoses were replaced.
Wheel alignment was performed.
The driver side drink holder was replaced.
The battery was replaced.
Rotors were turned and brake pads were replaced.
The rear decorative rubber bumper strip was reattached.
Air conditioner was serviced.
Oil and filter were changed.
Air filter was changed.
The valves were adjusted.
The fuel filter was changed.
Since the original maintenance was done, I replaced the starter in 2005 at about 120,000 miles.
The air conditioner compressor was replaced in 2006, and I've had to service the climate control system with freon yearly since that time.
The battery was replaced in 2008.
The vacuum lines, by which the automatic door locks work, evidently formed cracks, resulting in loss of the automatic locking feature in 2008.
The controller located on the top, center firewall that operates the climate control system, failed in 2008 at approximately 138,000 miles. I had the unit replaced with a manual valve, so that when I want AC, I close the valve manually. When I need heat and/or defog, I have to manually open the valve.
At 153,000 miles, I had the rotors turned on the front brakes.
At 153,000 miles, the front right wheel bearing was replaced and the front left bearing was repacked.
At 153,000 miles, the exterior paint still looks good, but is fading. The color is a pale yellow (tan).
At 153,000 miles, the camel tan vinyl interior still looks almost new, but has a couple of rub areas on the left side of the driver's seat.
At 153,000 miles, the engine leaks a small amount of oil; not enough to get excited about, but uses no oil between scheduled services.
I bought my 300D because I had always admired the car's clean lines and because I liked the smoothness of the diesel engine out on the open highway. Everywhere I've gone in my 300D, people have stopped me to comment on it, often saying they had owned one and regretted having sold it. They are surprised when I tell them it is a 1984 year model, because it looks almost showroom new when cleaned and waxed.
My wife and I have used our old W123 300D for road trips to Gatlinburg, TN, Branson, MO, Washington, DC, and other distant destinations with no hesitancy about its age. It has never let us down. We continue to use it for long trips and as a daily driver. We have averaged 32+ miles per gallon in normal highway driving conditions, perhaps because I drive conservatively speed-wise.
In addition to being thrifty fuel-wise, the 300D has excellent suspension and seating systems for long trips. We are not road-weary when we reach our destinations, something that cannot be said about most other cars.