Lawrence,
It's a little difficult to answer your enquiry, because there's no such model as a 2008/9 'Jazz Comfort' in the UK, so I don't know the spec of your wife's car. The 'USB' socket on the upper-range UK Jazz models is actually a conversion lead, with USB female at one end, attached at the other end through a plug to a further socket. I don't know what you'd call this type of plug and socket, but it's located just in front of the gear lever, at the foot of the dash, hard to see from a seated position.
I really can't say whether it is then hardware, firmware or software that interprets the signal in, and the control signals from the user, nor whether it can distinguish between a USB device with a FAT filesystem, and an ipod. I'm afraid I live in a PC/Windows world, and don't use an ipod [I have a 'Cowon i-audio' player - bit esoteric, function over form], so I can't test it out. Others on this forum seem to have a better idea about the use of ipods.