I suggest you pick something that's not vehicle-related. Something that's been true about you for a while and will probably continue to represent you for several years to come. Maybe sports-related like a favorite team, maybe a hobby?
I became Elvis because I'm near Memphis and I love old Cadillacs. This year I became "The Dogfather" for a short time, which is still a good one and will always apply.
I was just "Pete" on all the Honda/Acura boards and I still go back to that name on a baseball forum I visit. That's a small group (< 50) and we all know each other pretty well so it's easy to keep up with the name changes. We change names all to time to end losing streaks. (We're Detroit fans and they suck.)
This is the last place I still use Elvis. With the avatars I could continue to use Elvis pictures and everyone would still know who I was. Plus, it seems like now might be a good time to make a change.
I don't know, is it even possible to change names here? Or would we have to create a new account? I guess a SuperMod should know these things.