The 20th January 1957 saw Stirling race both a Maserati 450S and a 300S in the first round of that year’s World Sports Car Championship on the Costanera road circuit, which used the wide service roads of the Aeroparque Jorge Newbery in Buenos Aires, Argentina.
The 1000km race took place over 98 laps of the 6.29 mile circuit and would last over six hours in total. Stirling's first impression of the circuit during practice was that it was extremely dangerous, being bumpy and poorly marked.
He shared the Maserati 450S with Juan Manuel Fangio, and the car proved to be very quick, with Fangio posting a lap with an average speed of 114mph, causing the organisers to install a make shift chicane to slow the race cars down a little.
Although Fangio qualified the 450S, number #2, on pole, it was Stirling that started the race, making a clean getaway from the thirty car grid and pulling out a 20 second lead over Masten Gregory's 3.5 litre Ferrari 290MM, that Gregory was sharing with Luigi Musso and Eugenio Castellotti.
After two hours in the lead, he handed over the 450S to Fangio and all went well until the Maserati’s clutch and gearbox failed, meaning for the moment both were out of the race.
Just over half way through the race, with 33 laps to go, Stirling took over the Maserati 300S, number #28, being raced by Jean Behra and Carlos Menditéguy, which was running third, some two and a half minutes behind the Ferrari of Alfonso de Portago. He started lapping 10 seconds a lap faster than the second placed Ferrari and caught it before the end of the race.
Stirling finished second in race, just over a minute and a half down on the winning Ferrari 290MM driven by Gregory and Musso, although he won his Sports 3000 class.
The following day, Stirling flew out on a Short Sandringham, similar to the one in the image above, a civilian passenger version of the Short Sunderland flying boat that had operated in WWII, enjoying a pleasant flight from up in the cockpit to his destination in Uruguay. He returned to Argentina and Buenos Aires the following weekend to race a Maserati 250F in the city’s Grand Prix.