Is it an Exener design at all? Looks like a proposal for the Dodge Dart, and that bonnet bulge that becomes the instrument panel is reminiscent of his Plymouth Assymetrica design
It's not by Exner, no, but the designer was heavily influenced by him and worked alongside him.
It's not actually a specific proposal for any particular car hence my previous reply that it wasn't a Plymouth XNR as it does have a (not particularly imaginative!) name which is neither Chrysler nor Plymouth but which you've (almost) already mentioned, so you have partly answered the question already! It was of course designed under their umbrella, but who was the designer?