I had a horrendous squeaking coming from what appeared to be the dash area but found it was the rear. On investigation I noticed the small rubber 'bumpers' on the rear parcel shelf which hold against the rear hatch had a polished appearance. Just rubbing them with my thumb brought them back to a matte appearance - result, no more sqeaking! I'ts not a permanent cure but when the 'squeak' re surfaces just repeat & the squeaking stops (for a while!). I have yet to find a cure for the rattle under the passenger seat which is present when no one is sitting in it! Any suggestions please?

if maybe you can find a little silicone spray, might help with the rubber a bit longerterm?..

and the rattling,thats probably the seat slider lever/handle thingymobob, try tie it up with a thick elastic band, worked on my old corsa, not had that problem with my Aygo yet though

I have noticed a rattle from my passenger seat when it is in the fully back position. Just moving it forward on to the next "notch" seems to remedy this. I haven't worked out what causes the rattle, but have come to accept that a great value car like this will develop squeaks and rattles over time (my 08 is now up to 33000 miles and doing pretty well!)

I've had a rattle that was bugging me,I was sure it was one of the front seats,it turned out to be the handbrake.
I just touched the button whilst driving and the noise disappeared!