I was going to call mine the "Green Hornet", but I noticed that someone was already using that, so I call my 2000 Citrus, "Elroy". Looks like Justin calls his that too, but I guess they have different last names.
We've always called our citrus the little "Green Hornet". People rarely have a completely unique name. If people can routinely share a name, it seems alright for cars to share one too.
I suppose the only difference is that one silver Insight is going to be nearly identical to another silver Insight and a unique name helps to give the car it's own identity, if only in the owner's eyes.
Speaking of silver Insights, we still have not settled on a name for the new silver baby. We just keep calling him "silver", which is pretty lame...at this point we have ruled out Skeletor and Sunshine.