Dealer says it is and therefore say they can't put SB wheels on a sedan. I can't find any specs to confirm it. The sedan is wider so it might be true. I'm going in again next week. I'll see if the dealer can tell me.
Not many of the wheel options for the Saloon are listed in the parts catalogue but the CF7 and COX options are and they are both 7.5J x 17 size and the offset (ET) is 56. With same 7.5J x 17 size on the 3-door and Sportback the offset (ET) is shown as 51. So it looks like your dealer is correct.
Crikey, even more exclusive...
Would that account for the measurement taken from the centre line of the wheel being wider than the SB though? The saloon is 1555mm and the SB is 1542mm, some 13mm difference...
The one dimension that is fixed in MQB is centre of front axle to pedal box, and only longitudinally. This also fixes engine position, and bulkhead. Everything else is up for grabs.
The mechanical parts are just about the same, but the body dimensions are unique to the Saloon as is the front and rear track and, by 1mm, the wheelbase..