I drove one of those Lincoln Mark VIIs about 10 years ago when there was one for sale for about $1000. I wasn't particularly impressed, but I'll bet the BMW 524TD would be a different story. I remember seeing one of those too for $700 about 5 years ago, but by then I was buried in MBs.... Problem with either was they only came with ZF slushboxs
I owned one of these lincoln diesels for about 5 months once. IMO, when the air suspension is functional, it can't be beat. I was in the midwest at the time, and the car was a big, floating fuel sipper with sinfully comfortable seats, and a awkward little trunk. All the digital stuff was a problem too, had some issues with the oil pressure sensor throwing false readings every 30 seconds.
As far as a highway cruiser, it was above and beyond my 300D, it was faster, more comfortable, way better fuel economy, better ride, ect. However, as a full piece of engineering, is was not as well done. Its a huge car, and the trunk pissed me off every time I opened it, comes with a mini spare that was sort of thrown in and bolted down in a very awkward space. The car wasn't really refined, it was great and superior in many ways, but over all, an inferior car to the 300D.
I can't say enough about how awesome that air suspension is when its in good shape though. I happened to go down the same 50 miles of rutted dirt road in both cars, and the 300D could barely make 30mph and was rattling the heck out of you at that speed, while the lincoln could do an astonishing 70.
Ironically, at the same time, my friend was big into 524TDs and had two of them, and for the same engine, power, speed, and economy, the feel of the car was so amazingly different. Those 524s have a nailed to the road lead sled feel that is just great. If you can find one, those are awesome cars. I wasn't too hot on the engine as far as maintenance, it came nowhere near the durability of the MB iron block/head double like timing chain, but it was a very smooth powerful diesel.