Thanks for these replies so far... Our first hunch was also Mercedes due mainly to the shape of the radiator and the badge which, though hard to distinguish, hints at Mercedes... but have not found another photo that matches all the features of this car... The flat ends on the front fenders, rectangular back window, flare on end of rear fender, lamps at base of windscreen, the wire wheels... etc.. Looked at Cadillacs, Dodges...
What are the chances this is a one off coachbuilt car vs. a production body?
Thank you