Rate my game art pls!

I want your opinion on my art. I have a project for an idle game with a 2D side-scroll pixel art theme about buses. There are currently 50 buses, but I'm not sure if there will be more. The game will be commercial and cost around $5. What do you think of the art?

Picture of 4 of them: https://postimg.cc/rRSYSyfq