I'll out myself now. Bought an '06 Magnum about two months ago, and while I wanted a car with potential Ecto conversion in mind, it wasn't the primary concern. I just wanted a decent car that would replace my '02 PT Cruiser with 200K miles.
My Magnum is a daily driver, so any Ecto trappings will be temporary: that means magnets and eventually a lock-on roof rack. It's just too nice of a highway cruiser to saddle with the extra weight and drag.
What using magnets does afford me is the ability to trick out the car on a whim in just a couple of minutes. It's more of a Ghostbuster staff car than an Ectomobile, really, but it does get a reaction.
I've gone in two phases so far: phase one was a set of three no-ghost logos, two 14" ones for the doors and an 8" one for the hatch. Phase two consists of 3/4" strips with yellow and black caution tape on the hatch and along the rocker panels.
In both cases I received horn honks and thumbs-up from other drivers within five minutes of getting on the highway. That, I learned is how powerful the concept of the Ectomobile is with the general public, and how lasting an image it is. Here I am with a white Dodge Magnum with a few magnets on it, no roof rack, no greeblies, not even a GB uniform worn by the driver, and yet folks are going crazy for it.
Gimme more.
"Why worry? Each one of us is carrying an unlicensed nuclear accelerator on his back."