There have always been some sort of "corporate look" orientations in car dealerships, no matter which OEM it was. Usually, it was the signage that did the trick, rather than specific architectural features. EACH one had "personality"!
Since about the middle '80s, the OEMs have had more control of how the individual dealers look, by observation from a GM point of view. Outside architectural features, colors, materials, etc. are in a menu for the dealers to choose from. Even the interior furnishings have to be signed-off on! And, in the case of our former Nissan store, WHERE the chairs on the showroom floor were located. Have to move the KeyTrack machine to a storage room, BEFORE Nissan would sign-off and write the final check.
The modern franchise agreements state how the store should look and operate. Standardization is the key, it seems, plus corporate training of how to "act" (via online training, etc.).
Prior to the appearance of the Chrysler LH cars, Chrysler had a corporate training program called "Customer 1", which also came with a training manual. It was designed to orient the dealer people/employees to the fact that they would be seeing some NEW customers like they hadn't seen before AND how to treat them. Of course, there had been MasterTech programs on how to treat customers since the 1950s!
Buick had one in the later '80s termed "Living the Vision: Exceeding Customer Expectations". The dealer principles and upper management got a three-day version. All other dealer employees got a one day seminar. End result, everybody from the dealer principle to the service porters got the course. It was a good one. Part of the earlier compliance with employee training requriements.
About five years ago, a Chevy dealer in the midwest remodeled his store to look similar to a Bass ProShops store. It was claimed thatthe customers loved it and sales increased. But several months after it was finished, GM/Chevy came out with their new corporate image program and HE had to comply. He tried to fight them, didn't "win", and sold the store as a result.
Dealers have a LOT more hoops to jump through with their OEMs, more than ever. BUT there are financial pey-offs to do so, too! For a larger dealership, those "carrots" are VERY substantial! Most of the remodels are subsidized by the OEMs, significantly. So, that's how they seek compliance.
There are a few coffee table books out on car dealers of the 1960s and such. Quite intersting, with lots of memories in them. Some of the larger-city dealerships were quite ornate and beautiful. As many were in downtown areas, few are left today.
Enjoy!
CBODY67