Parking won't be a problem assuming you are both together in the car. It won't matter who is driving, but she will have to be present. In my experience, I have had cashiers at restaurants and shops look at the name on my pass and sometimes thank me by name. If you both have male/female sounding names then this wouldn't be a problem because they wouldn't know whose pass it is, but assuming your names will give away the fact that you are using her pass (ie. you don't look like a Sally), then they could ask for her to be present. If you are both there when the purchase is made, then it won't matter who holds the card and who hands over the money. Finally, the cashier might not care whose name is on the pass, but you never know.