Sorry to be pedantic, but the builder of the car was Ernesto Maserati according to my source, pictured with his wife and son Alfieri.
I would also like to apologise to Wendax for appearing to use his guess to gain an advantage - I only noticed his post after I had found the puzzle source. A bit embarrassing. I have not shown a photo of the actual prototype of the A6 because we've not had that car as a puzzle, and I can use it at a later date!