One of the reasons the industry hosts auto shows is so that us media types can see all of the new cars ahead of the public, in order to write about them and expose the public to the new models on the market. That means that there are always photographers on hand to document the show, even back in the early days.
Take for example this fantastic shot from the 1912 auto show at the Toronto Armouries. This booth is for the American Underslung, a car built in Indianapolis by Harry Stutz from 1905 until 1914. The name came from a unique suspension design which allowed the car to sit much lower than other cars of the day.
Source: Toronto Archives