I submitted Pixar Grand Prix before I left for work. I learned that you need more wide open spaces for tracks. I have a few spots on tracks where if you have to be reset, it may reset you either closer to the start or end of the track. I have successfully gone around all four courses without resetting in the wrong spot so I know it is possible.
EDIT: Toy box is now available...
Pixar Grand Prix
Welcome to the first running of the Pixar Grand Prix. There are four races from famous Pixar film locations. Race stops include Radiator Springs, Nomanisan Island, The Axiom and The Monsters University campus. #SpeedwayChallenge
edit: There are a lot of entries this week. I just did a search for "#SpeedwayChallenge" on the site and it brings back 50 boxes. Mine is NOT on the list. I think MightyGitis is going to be streaming a lot tonight!