I realise this is a GM dribble site and all, but absurdly grandiose claims like this can’t be let slip through to the keeper.The only, and I mean only thing, RR had over Cadillac in the '50s & '60s was a higher price.
Product-wise, RR wasn't in the same strata as Cadillac, it wasn't a competitive product by any criteria.
A friend owns a '54 Bentley; it's an awful car.
Eg: 1965 Rolls Silver Shadow featured:
4-wheel hydropneumatic suspension with IRS
4-wheel disc brakes
No contemporary Cadillac offered any of the above qualities, not even lowly front discs!
Rolls famously featured hand built assembly.
Whereas GM’s finest were little more than formulaic, tarted up, mass produced Buick/Olds/Chev etc.
Hence in which specific criteria except chrome and glitz was the new Shadow uncompetitive against its corresponding 1965 Cadillac, as per your claim?