When the zombies break out, you really need something that can drive. And when I say drive, I mean as fast as hell!
You can easily open the top of the bus, so you can play inside it. You have to pull the turret backwards before you opened the top. There is enough room for at least 4 minifigs: There’s a bed, one chair, and a computer. The bus is very playable.
There’s also a slide able door. You have to remove the fence first before you can slide the door. The minifigs are now able to step out of the bus!