I would take into consideration that it could be an non-sport-edition Z3 after all. Found the car on ebay and according to the pictures, there are a couple of things that aren't quite original in my opinion, for example the plastic covers next to the fog lights have been painted as well as the 'sport edition bumper mesh' ( I have no idea how it's called
), or at least it looks like it has been painted, pictures are of poor quality. Chrome side vents weren't part of the sport edition as far as I know, eventually the wood trim looks original to me so it's not a part of the sport edition either. Could be a sport edition Z3 with a different center console, but as well might be a regular Z3 with some retrofitted parts. The VIN of the car would definitely be helpful.