By Alex Lauer You need to watch this trailer. No, I’m not talking about the new Game of Thrones, and certainly not the new Lord of the Rings or whatever the latest superhero Marvel has excavated happens to be. No, the most exciting trailer of the summer, as it stands, is from Cadillac. Specifically, we’re talking about the Project GTP Hypercar, which Cadillac unveiled on Thursday with a minute-long video that puts the Batmobile to shame. But this car is very much real, even if it’s hard to believe it’s a Caddy. The prototype hybrid race car is set to compete in the IMSA WeatherTech SportsCar C…