Things to happen on a road trip?
They stop at a roadside attraction to see the world's biggest ball of yarn and get roped into a meeting for timeshares in Panama City Beach, FL. In the end, they decide not to invest.
You're a writer who can't think of any content for a chapter? In what way exactly do you qualify as a writer then?
They Pelted Us With Rocks And Garbage
They get buggered by the ghost of Neal Cassidy. Here is an idea, if you're this naive about the world, quit writing about the world.
Flat tire, stop to take pictures at a scenic place, get lost, detour to see something interesting (but argue about it), have a fancy dinner, help a stranger somehow
Writers use their own imagination to come up with ideas, they don't ask strangers. Go watch a few road trip movies or scour some some stuff on YouTube. Hell, go read Jack Kerouac's On the Road. There's so much out there about road trips and the things people do on them. Go look for it and use your imagination.