Poor writing.
I really dislike this movie, even though I loved the 1st one. There's 1000s of things that really bother me in this movie but one is this:
I Cannonball 1, Burt Reynolds was considering several possibilities for a car including a police transam and a limo with diplomatic plates, but ends up rejecting them...
Now why does he reject the idea, but later comes to use it in the next run around? Did he not think of anything else interesting?