This isn't exactly about audio in my Challenger. But working on the car is fun only if you're in a pleasant environment to do the work. I finally got sick of the poor radio reception and endless/repetitive commercials on the stations. A CD player doesn't work, because the CD always runs out when I'm under the car, and loading CDs with greasy hands isn't a good idea. I spent the weekend wiring up my shop with ethernet cable. The ethernet cable is connected to my home network. The shop end of the ethernet plugs into an Audiotron box, and that box outputs to a pair of self-powered speakers picked up from a computer store.
The result? I now have access to my entire music collection in the shop, plus internet radio. Aaahh! Next I should add a refrigerator, and then I'd never leave.