When I ordered my Twizy i wanted a waterproof cover as I thought that i might not use the car that much in the middle of winter. What Renault supplied was an indoor thin dust cover that is not waterproof at all.
I gather that they are working on releasing a full waterproof cover and they have promised to swap it out for me when this is released but word of warning to check the cover before you buy it and ask if it is waterproof or not?