A playboy Hollywood producer must embark on a roadtrip from Hell with his long lost rebellious son. What will happen when these opposites are forced to attract.

What is the inner journey going to be?

The outer journey should act as a metaphor for the inner journey of the MC (especially in a road trip movie) as such what is the starting point for the MC? What is the inciting incident? And what is his flaw?

As DPG mentioned the odd couple road trip has been done a story such as this needs a good inner journey to empower the character and increase audience interest. In this instance if you were to describe the inciting incident, character flaw and goal clearly the reader could imagine the charters's trajectory and understand he will have an arch throughout the story.

Hope this helps.

The only thing I can add is don't state the question you hope the reader has in their mind. It is heavy hand and makes your writing feel like it has failed to prompt any sort of question.

As the others said.

The Odd Couple Road Trip is a trope as old a "It Happened One Night" (1934) and as recent as "Guilt Trip" (2012). The trick is coming up with a new twist, something that hasn't already been done.