Depending on what you plan to use your roof rack to carry, i would advise to get a rack which uses suckers 4 little pads that attach really easiy and quickly and packs up into a shoe box size pack.
i have owned both types and use this for surfing quite frequently and trips to b&q etc. it can also benefit from fitting all cars.
The Fiat specific rack is good but i found it fidly and time consuming to fit and also had the tendancy to damage the paintwork
do a search on e-bay sure to be on there think mine came from California.