I'm currently an Undergrade working on Placement with PLC's. Came accross this article while researching, which you may find interesting if your thinking about automated parking:
Unitronics - Automated Parking Benefits
As for programming as far as I'v come accross there often pretty similar, although I know the likes of Siemens use prepiatory software for programming which likely means they have some differances though not got any experiance with it.
Hope that helps?