Judging by the color, numbers and number placement; I believe this is the Boyle Valve Special which won the Indianapolis 500 in 1939 and 1940 In the hands of Wilbur Shaw. It only lacks the “The Boyle Special” markings. As the number 1 it would be in the 1940 livery. It was the first European car to win the 500 in two consecutive years. This year it ran a lap of IMS before the 500 in honor of Maserati’s 100th anniversary, and the 75th anniversary of it’s first win. Historical side note: After World War II Wilbur Shaw was instrumental in saving IMS from being sold to land developers and turned into a subdivision. He served as IMS president from 1945 to 1954.
And its a beautiful car. Cool trivia, Thanks!
i thought it was fangio`s car at first till i saw the 1939 bit which wouldve been just as cool 
i also mistook the brabham for jim clarkes lotus 49 at first glance
gonna enjoy both cars and live in hope of driving the cars i mistook them for
Indeed, the Boyle Special is now in the game. I plan on creating the livery in the next couple days unless someone beats me to it. Great observation Eurocarnerd.