Since I love the movie, I have to point out that How to Train Your Dragon is from Dreamworks, not Disney!
I left my car at the default serial number for several years before settling on "Serendipity," which I consider one of the prettiest words in the English language and quite appropriate for the driving experience.
I've thought about changing it to "Slug" because the old S60 model is the slowest Tesla ever made, so far as I am aware. Can't bring myself to do it, so Serendipity it is. I've put more than 87,000 miles on it in the four years since I bought it used. It has been my only car that entire time.