Marcel Robert is the author of the book Îles sans voitures (124 pages, 2013), that’s Carfree Islands in English. He starts out with nine carfree islands in France, moves on to Sark, then to the islands on the western coast of the Netherlands and Germany, a big jump over to the Croatian islands and one Greek island (Hydra), the Turkish islands in the Marmara Sea, a couple of overseas islands and then, finally, Venice.
It is a lovely book with beautiful photographs. You can read it on Blurb here: http://www.blurb.fr/books/4733679-les-sans-voitures, or order a printed copy. Too bad it is only available in French.
Marcel Robert has also created a list of carfree islands on Wikipedia https://fr.wikipedia.org/wiki/Liste_d’%C3%AEles_sans_voiture. There were some European islands missing, I added twenty. To me, the list still seems incomplete when it comes to Estonia, Scotland, Ireland, Finland and Italy. Do check the ones of your own region!