I have searched for other threads on this but most ppl seem to have both USB and AUX inputs. I only have a USB input. I have looked on the SEAT website and can only find leads to suit cars with USB and AUX inputs.
The FR550 was a special model produced before the Leon facelift. Up to that time you had to choose
either iPod or USB ports and they were both optional. (Only since the facelift has the centre-mounted USB and iPod connector existed.
If your car has the USB port, it'll only interract with memory sticks and some basic MP3 players, nothing Apple. To be honest that's probably better, because with the iPod connection from the same period you would struggle to fit a newer (since 2009) iPod...