South Lyon had a Chevrolet dealer on Pontiac Trail, now Tenpenny Furniture. West out in the late 60's/early 70's. Can't remember the name though.
The old Bili Root/Roger Peck Chevrolet showroom was on Grand River across from the Burger King in Farmington. Erhard BMW was there in the early 70's.
But earlier than that, in the summer of 1970 a new Oldsmobile dealership opened. It replaced Pioneer Oldsmobile which is now a shoe store on the north side of Grand River in downtown Farmington.
Unfortunately, they did not last long. Best Oldsmobile. The GM strike came along, you know the rest of the story. In fact, for awhile the only car on the showroom floor was a model car.
Keego Harbor had a Pontiac dealer on the north side of Orchard Lake Road. Closed in the early 70's. Their claim to fame was the parts department was open 24/7/365. Went once on Thankgiving night to get a set of points for my Chevy. Had to, quit on the road.
An earlier post asked about the Buick dealer at the Lodge/7 Mile. Morris Buick, the last incarnation was Prat Buick in the late 80's. Near Woodruff Oldsmobile and Gene Bell Chevrolet. Woodruff closed in about 1990, I worked the termination invertory in there. There was a basement there, flooded with about a foot or two of water. Gene Bell, not sure when they closed, they were still around when I left Michigan in '79.