First, with these old diesels, condition is everything and I'd avoid the automatics.

Most of my diesel experience has been with 240Ds.
My first was a tired rustbucket with an automatic. After rescuing it from the PO's teenagers, I was able to make a decent driver out of it. It will run at 65-70 but it's very noisy and unpleasent at that speed. It's fine for local errands & yard sales though.

My second 240D, was even rustier. But in better shape mechanicaly, with a four-speed stick. So much nicer to drive and acceptable on the highway.

My third 240D is also a stickshift, with a solid body and a factory replacement engine. It's the nicest driving of the bunch. When revved, this diesel actually sounds more like a gasser, with less of that typical diesel racket my first two had.
I'm keeping this car in Virginia Beach now and regularly drive it, including some highway miles. I'm pleased with it's performance, though with few hills to test it there.And it's not my sole Virginia Beach transport. When I'm there, I have other vehicles availible for rush-hour or really crappy weather.

FWIW, a W110 diesel has about 10 fewer horsepower, but also weighs about 300-400 pounds less than a W123 240D. Late 190Ds and all 200Ds had dual circuit braking with front discs - much better than the four-wheel drums on earlier fintails. The slightly larger 200D engine with a five bearing crank may have a slight edge over the three-bearing 190D unit. Original top speed on a 200D fintail was around 80.

Happy Motoring, Mark

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DrDKW