The MC Tubarão M3 GT4 is based on the BMW M3 GTS model that raced in the Endurance RS championship during the 2015 season in the GT2 class, composed by former Maserati Trofeo cars as well touring car specials. It has slightly different specs of the M3 GT4 present in Project CARS, but both have essentially the same body.
Just unzip the file into Project CARS main folder and it's good to go.