Yep. As an MC, I'd say no Driver, no Bus. Otherwise, your character isn't really stepping away from that life. It's not "I'm the same character, but now I have these moves as well." It should mark a pronounced change in the character.
That said, I, as MC, would work with you to find a reason why you don't have the bas anymore.
"Hey, Chris, I''d like to change playtypes, but I don't think I could have BillyJoe drop the bus and keep my character real. He just never would."
"Well, what are you thinking of switching to?"
"Faceless."
"Ah. Well, of course, you're in the bus one night, sleeping there like usual, when the raiders from over the hills set fire to that bitch. How full are you on gas right now? Pretty full, right?" etc.
Like any improvement, it doesn't have to spring into fiction as soon as your pencil is done marking the x next to "change character type".
Do it to do it.