We had a Java Green Beetle when I was a teenager. It had several accidents and was eventually written off when someone drove out of a junction and hit it through a lampost and a hedge. But IMO nothing to do with the colour.
I love Connaught Green and it seems to be a much admired colour when I park the 4/4. Even watched out of a cafe window as a teenage girl took lots of photos of it the other day (couldn't get out in time!!!! or was it the wife's look?).
Definitely not superstitious - but I go berserk if someone puts shoes on a table or opens an umbrella indoors.