While I merely want to post my challenge, feel free to post yours, and I'll make a list.
You have to post proof that it's possible
If you managed to complete a challenge - don't post the solution, only challenger is allowed to post solution
I'll (obviously) start:
CHALLENGE: I challenge you to get a car up on Franklin's house:
just a friendly tip: you can make the car fall faster, brake faster and accelerate faster if you use Franklin's ability
by fall faster I mean, if I fly at an arch, and hit the slo-mo, it will drop much faster and as if gravity is much much stronger, useful for not overshooting
With a little bit of creative thinking(and no cargobob...), it's easy so I'm not going to post a solution to this one. just saying it's possible