I remember Prossers in St Georges Rd, it had a wooden vehicle lift that went up to the floors above from street level.
The other one I remember was Milngavie Motors when they built on the site of the Star cinema (I think it was), just along Maryhill Rd at Bisland Dr. They then moved out to Temple and their showroom was flattened for flats.
There was a Ford dealer at the bottom of Elmbank St, but I can't remember their name (perhaps Skellys), my Dad bought his 1964 Ford Corsair (BGB 102 B) from them and every Sunday we'd walk down to look at it in the showroom as he waited for his HP to clear.
Callandars had a tiny showroom on Gt Western Rd near Goodies at the Botanic Gardens - they sold expensive cars such as Aston Martins.
Ninian Sanderson's in Gt Western Rd daughter had the registration number LUC 1 E - worth a bob or two back then as well I'd imagine.
Ross Motors had a motorcycle shop in Gt Western Rd, just up from St Georges X.
Scottish Motor Services had two showrooms at Charing X, both opposite each other. The one which is gone now was where the father, Mr MacKinnon used to sort old classics and then put them up for sale. I still remember seeing a little fireplace at the back where he had the fire roaring up the lum as he fettled an old MG TA. They were the agents for the Clan Crusader in Glasgow back in the 1970's.
You can take the man out of Maryhill, but you can't take Maryhill out of the man.