Any commercial cleaner for fabric and other for leather will work, please, just test it before in a small area.
My i3 has full leather seats and I use Griot's Garage Leather Spray and for the fabric and plastic on doors, etc, Griot's Garage Interior Cleaner, here are the 2 links
http://www.amazon.com/Griots-Garage-10994-Leather-Spray/dp/B00IUE5S5U/ref=sr_1_5?ie=UTF8&qid=1413995631&sr=8-5&keywords=griots+garage+leather+care
http://www.amazon.com/Griots-Garage-11104SP-Interior-Cleaner/dp/B00J5CVOZY/ref=sr_1_1?ie=UTF8&qid=1413995804&sr=8-1&keywords=griots+garage+interior+cleaner
Hope this helps.
Have a great day !