I have three kids: two boys, and a girl. This means I've watched a lot of movies designed for children that I might not have chosen to watch on my own. Some just outright suck. Others are excellent opportunities to learn something I can use in my writing.
CARS is one of the latter.
If you haven't seen the movie, I suggest you watch it with your writer brain and pay close attention to the plot. Go do that, and come back. Just kidding, you can keep reading even if you haven't seen the movie.
The inciting incident in a story is the one that propels the story. If the inciting incident doesn't happen, the rest of the story doesn't happen. In CARS, it's Lightning McQueen falling out of Mack's trailer and getting lost on the highway. If this doesn't happen, he doesn't get to Radiator Springs, doesn't learn any lessons, and doesn't change.
The inciting incident is often something that passively happens to a character. Which isn't terrible, if the rest of the story happens because of choices actively made by your character. But in CARS, the inciting incident happens because of the main character's flaw. I'd say that is probably the strongest way to start a story.
Lightning McQueen is a selfish a-hole at the beginning of the movie. He forces Mack to drive through the night to get him to his race, instead of allowing him to sleep. He promises Mack he'll stay awake with him and keep him company while they drive, but instead he falls asleep. Finally, he surrounds himself with all kinds of crap that reminds him of how great he is (remember, the trailer door opens because a stupid Lightning McQueen toy falls on the switch).
Lightning finds himself in a pickle (or CONFLICT, the heart of all stories) because of his flaws. He spends the rest of the movie trying to overcome those flaws. We get to see how he slowly becomes less selfish and more mature, which makes the ending feel completely earned instead of rushed. Of course the new Lightning would have the heart to lose the most important race of his career. We have spent the entire movie watching him become that person (or racecar, if you will). He has earned his new heart.
(Don't get me started on the ending of CARS 2, which is a post for another day on how NOT to earn an ending.)
How can you apply this to your own writing? Examine your inciting incident. How does it come to pass? Does it happen to your character, or because of your character's choices? How does it affect the subsequent choices your character makes over the course of the book?
Incidentally, the inciting incident is also an important part of your query letter. You must show in your query what the inciting incident is, and how it's going to affect your character over the rest of the book. Writing the query letter can help you evaluate the strength of your inciting incident.