I've got an existing NCP ParkPass Card account, if I register for a new ParkPass App account, does the introductory discount apply to my card?

No, the introductory discount is only applicable when you register for a new ParkPass App account is only valid for payment made with the app. Any new accounts on the ParkPass App operate completely separately from your existing NCP ParkPass Card account including any discounts you are eligible for. This also applies to any special SaverID rates which you currently enjoy using your NCP ParkPass Card i.e. they are not available on the ParkPass App at this time.