I'm in the process of trading my '87 300E with 367,000 kms (228,000 mi.) for a '94 E420 with 181,000 kms. (112,000 mi.)
Seeing some of the higher mileage cars here, I kind of think my 300E has alot more miles in it. It still gets 32 mpg (Imp) on the highway, with lots of power.
The problem is, there are cosmetic issues with it that would cost more than the upgrade is costing me.... a window regulator, sunroof motor, vacuum lock system, valve guides leaking, transmission front seal leak, air conditioning.
Its a shame, because I think the 300E is such a great car. Incredibly, the curb weight is about 600 lbs less than the E420. I think what has to happen is that more have to come off the road before they begin to be appreciated, the same way a nice W123 has gained in value, harder to find than it was a few years ago.
I don't want anything for my '300E, but I do hope I can find someone who could use it as a project, etc.