Before you extend the wires or get busy buying wire you must figure out where the items will be setup. You can literally put any item anywhere you would like, given functionality and style, except the Ide cable. The Ide cable has a limit on how long it can be while still functioning correctly. I bought my custom cable from
stone wall. Order a cable with the longest distance being from the motherboard to the hard drive because then you can tuck the hard drive under the carpet or anywhere incognito. Unless your seat is high enough to house the Xbox with the hard drive in it. You should figure out where you want the dvd drive and the Xbox, make sure it is not more than 48 inches and somewhere in the 48 inches plan where to put the hard drive. Anything else can go wherever you would like. Ports built into the console or in a cubby in the car. Whatever you want but be creative and buy a dremel to make precise cuts.
Don't Forget: This picture does not included the A/V cable.