'Fly, with the only limited market of the very wealthy in the U.S, the Royces (car guys, especially those from the Island, will know why you don't call them Rolls') and the lesser-badged Bentleys, comparitively few higher level imported sedans found ultra popularity here in the upper-luxo market in the era you mentioned. The number of other elites who wanted a Jaguar or Mercedes or similar, desiring a notable car without outrageous expenditure, chose so, but remember, at that time, even if you HAD to have a notable ride, you'd eventually get tired of (shall we say) a day-to-day reliability problem plus waiting for service and imported parts. Even big-titted movie stars who'd gladly pay Juan the pool-boy extra for a mid-morn frolic would eventually get pissed when her "Marquis de Marquis XJ
" wouldn't start to get her to the afternoon martini with Juan the pool-boy II
In parallel, American luxo-boats had the same minus-signature with the added negative of size overseas. The Lincs and Caddys of the era where simply too much of a footprint problem on the tiny (almost dwarf-like in many instances) roads in Europe. Physical placement, turning radius, not to mention fuel required to power a 300% larger engine moving 200% more vehicle mass simply never caught favor in Europe irrespective of status. They wanted the uniqueness, prestige, of an American car mostly when offered in a more manageable form, like the Mustang (called T-6 in Germany because of a name copyright law), or an Impala/Catalina if you wanted a REAL big car. Usually, Caddys and Lincs and the rare Imperial were only "heads-of-state" or similar chieftan rides.
As an aside, the Russian ZILs (ZIFs ?) were large Packard/Mercedes (mostly Packard wannabe styling) clones that were reserved mostly for pomp and ceremony and were never really offered for general sale.
Europeans, irrespective of what country, have mostly been negative to American "decadence" in respect to autos. This has changed (ever so slightly so) as USA manufacturers make tippy-toe steps into understanding European psychological (and honest engineering) requirements. Although more USA upper-level rides are now being purchased overseas, I believe the ratio will still border on the insignificant chart just as it has been historically. For the few(er) elite, purchase and operating costs, as well as operational functionality will not be that much of a problem, but for those who can afford the bucks, even most of them will still be put off by excessive (for their environment) size and operational manouvreability today just as much as they were in the past.
My humble observations...I'm sure others can add/subtract to my opinions. Regards..Jack