When I had a driver in my game, I will admit, the PC pretty much had to work to shoehorn in the car's usefulness. But, y'know, it was something he could do. Like, driving from one part of the hardhold to another, rolling down the window to have a conversation with Newton? Meeting Dremmer's advancing gang in your car, leading the charge? Yeah.
If I were to do it again... the first thing I'd do is draw a map, and be like "Okay, why do people always come to YOU to drive them to THIS place, instead of some other punk with a vehicle?" "Why won't you drive to THAT place, regardless of how much jingle's being offered? How did the last person you explained that to take 'No' for an answer?" Etc.
And like the comment in the book about how the Angel works best if he's got some juicy motivations to work with other than "heal people when they need healing", the Driver works best if she's got some motivations other than "Drive people when they need driving". Ask her what she wants in life. And what stands in her way.