Yes! I went looking for a knitted car cover, and lo and behold, here is such a thing:
"biked by this in-progress art car in lincoln square. she said she'll be exhibiting the car as part of columbia's manifest (http://www2.colum.edu/manifest_2008/transmission.php) art festival may 16th! check it out!"
This festival is already past, but the photo is fun to see!