OK, first I'll tell you who the "mystery man" is, then I'll tell you how I know.
The man in question is named Glenn Morris. He won the gold medal for the decathalon at the Olympic Games in Berlin in 1936. He was a graduate of Colorado State University in Fort Collins, Colorado. While I was in Fort Collins on business over a year ago, a friend of mine (and CSU grad) out there who shares my interests in history and automobiles showed me this picture, which is (I believe) part of their historical archives. I had to contact him again and ask him for particulars about it, and I just this week heard back from him.
The picture was taken in 1936 at the auto dealership of Art Sheely in Fort Collins, Colorado, and the man on the far left is Glenn Morris. And if it didn't say all that on the back of the picture, I wouldn't have had a clue.