Dealerships are in no way 'distributors.' They are more equivalent to a mcdonalds, and the plant that processes chicken nuggets. It's not all that surprising that the plant wants a big sign, and they have no clue how the dealership signage program works, or that it's even a thing. In all honesty, it's probably a marketing intern trying to satiate his boss, who's saying 'we need some big ole signs like all the dealerships have!' Odds are, you'll spin your wheels, develop some kind of quote, and the intern will end up taking all the flak for his ignorant boss's plan if someone tries to submit it for a PO.
Additionally, not sure how these are manufactured, but I doubt I'd touch the process of making a 5' logo with a chrome surface without an established process, so this would be something I'd sub out myself.