PC Bug maybe?

[Freizeitfarmer]

Even if the bus is not repaired one still gets the event from Sam for his band-gig in the city inclusive bus-tour! How does this work?
That's not a big problem but I think it's confusing.

 

[ISSsloth]

You all ride Seb's motorcycle. It's a bit crowded, but everyone manages to fit.

 

[Ereo]

You also arrive in a bus from Zuzu City (presumably). I think only the one going to the desert is broken. You are just not interested in going to the city, so you never use it alone.

 

[ISSsloth]

You also arrive in a bus from Zuzu City (presumably). I think only the one going to the desert is broken. You are just not interested in going to the city, so you never use it alone.

I think that in the cutscene where you arrive you can see the bus break down when you reach the valley.