I saw the car in Pittsburgh in 1977 at a Calder Retrospective Exhibit. It started my love affair with BMW. Saw it again in 2016 at Laguna Seca & again in 2021 in the BMW super secret warehouse, I said, "good to see you old friend".
I think he designed the scale model and a professional shop sprayed the car. It makes sense given the paint quality. If you look at the warhol M1, Stella’s M1, Stella e9, and many other art cars, they are hand painted. The Calder car is a smooth spray job. He did look confused though.
Calder was either 77 or 78 when this film was made. As I recall it was his last project & was called The Calder Mobile at the time as he made brightly colored hanging mobile sculptures. He was born in 1898 & passed away in November 1976 at 78.
The "artist proof" Calder Car BMW recently made was for the Alexander Calder Foundation. It has subtle differences from the original race car yet the paint is the same quality.