This postcard is an advertisement for the movie Grand Prix. My mother, and later myself, worked for a cinema theater company near Detroit, Michigan, which showed the film after its release in 1966. I think it opened first in Michigan at the Summit Theatre in Detroit, which is printed in large letters on the lower reverse side. The reverse side's top inscription reads: "The International Star Cast of "GRAND PRIX" photographed at the finish line of the Monza motor racing circuit in Italy. An M-G-M presentation in CINERAMA."
Among the international stars of the film are American James Garner, Italian Yves Montand, Chinese Toshiro Mifune, English Brum Bedford and French actress Francoise Hardy. Actual Formula One drivers Phil Hill, Graham Hill, Jim Clark, and Jack Brabham made cameo appearances. The movie follows four Formula One fictionalized drivers through a race season. The movie won Academy Awards for best sound effects and film editing. It was one of the ten highest grossing movie of 1966. In 2006 the film was released in DVD version.
As far as racing movies of that era go, I prefer "Le Mans," starring Steve McQueen. It was not popular at the box office but it captures the tension and all-consuming passion of a race car driver. Le Mans was worth the admission just for the one quote from McQueen's character, Michael Delaney, who said, "When you're racing...its life. Anything that happens before or after is just waiting." To hear the quote, go here. The film is an explication of this quote.