A lot of them are very ambiguous! Perform a spin whilst driving through the warehouse... ok, so it took me about 20 minutes but FINALLY drove through at the right speed to perform my 360 whilst still going through the warehouse, BOOYA he cries!
Look at "help" videos later to see what some of the ambiguous challenges are, and I see what it ACTUALLY means... he drives into the warehouse, does a little spin and accelerates off again. WHHHHHAAAAAAATTTTT!!!!!! Whoever wrote that mission either doesn't understand 'whilst' or underestimated it... "Drive into the warehouse, perform a 360 degree spin and then drive out again" is much better!
I'm finding that with a lot of these missions, I'm reading them, trying them out then going "oh, it must mean somewhere else then?". Watch a video later and discover I was right, and that it just didn't trigger on any of the other 20 times I have done it. Its really frustrating!