Just to clarify that last post as it seems I confused someone.
*most* accessories that are made for automotive applications (radar detectors, CB's, 2 meter radio's, etc) are designed to run on 12vdc. Some of the other electronic devices we use are not (such as GPS, laptop computers, etc) are not, even though they come with a adaptor plug that will fit in your cigarette lighter. These adaptor plugs will step down the voltage to what your device requires, so you cannot eliminate them by hardwiring them into your vehicle as you will apply the incorrect voltage to the device.
If you really want to permanently wire devices like this into your vehicle, I suggest the following method (which I have used in the past, with no difficulty). Go to your local auto parts store and buy a aftermarket cigarette lighter plug, and wire that into your vehicles electrical system as appropriate for your application. Then plug the adaptor plug (for your gps or whatever) into the newly wired in cigarette lighter, and zip tie the whole mess under the dash where it is out of the way, and out of sight. This will accomplish the same goal (not having a ton of wires running out of your cigarette lighter), while maintaining the proper voltage to your electronic device.
Sorry for any confusion.
--g/t