The availability of good reliable parts is my biggest concern. It takes way too much time to search for good parts at prices more reasonable than Mercedes dealer prices.

So far I've been lucky in sourcing the parts for my 95 E300D that I think might fail within the next few years.

My rule of thumb for used cars is to try to get a good low mileage one that is expected to go about 150,000 to 200,000 without many parts puchased. Basically pricing about $750 for each 10,000 expected miles. In my long history of buying used cars the best ones were very low mileage, about 10 - 20 years old, and fairly proven history of reliability. I found a 72 chevelle with 17,000 at $3000. 71 Lincoln Continental with 19,000 at $5000, two 99 Aurora's with about 20,000 & 45,000 miles for about $4000 each ( teenage girl T-boned the 1st one at an intersection - she was on the phone ). 89 Range Rover one year old for $9000 - first owner lost more than $30,000 1st year of ownership. Other criteria is garage kept so there is virtually no paint of plastic failure.

If a wiring harness could be found for the low mileage E300D it shouldn't take much money to make it a long term reliable car. I've spent about $2000 on parts & tires for my E300D & I think about that much to bring that car up to good reliable condition would be all that might be needed.

But the purchase price would have to be down to around $11,000 to be a reasonably priced long term car. When new Prius 4's are selling for about $26,000, more than 50 miles per gallon, virtually no mechanical failures for 200,000, quite a few safety features built in ( backup camera, radar sensor for rear sides and front, lane drift warning, excellent low impact bumpers, automatic speed adjust to match car in front with cruise control on ) We sometimes get close to 80 miles per gallon ( by computer ) for 20 mile trips. Today it was 63 for 20 miles home. It's hard to justify buying an older car that might be reliable and not cost too much to repair. My only complaint for the car is excessive road noise on rough pavement.