Last year at the X Games, Hot Wheels had Tanner Foust and Greg Tracy drive through a double loop, like the type we all made as kids. Except this time the cars didn't crash into each other and make a mess on your floor. This is how they did it.
Months of patient preparation are what made the stunt possible. There were RC test cars and a ton of crashes. But at some point, Tanner and Greg just had to get behind the wheel in order to make it happen.
Every detail is carefully examined and measured to make sure that, yknow, nobody ends up upside down and dead. It's amazing that they got this to work.
Here's the stunt as it was seen last year: