My 2nd gen didn't seem to charge well using the cable in the console, my 4th gen charges just fine, although i've noticed that plugging it in via usb cable to the nav stereo front usb port charges it faster.
blame apple, they changed the charing circuit in ipods at some point so older ipods only charge with older chargers / cables and newer ipods with newer cables / chargers. Basically they charge on a different wire in the cables now
my iphone wouldnt charge so I bought an adapter that allowed both charging wires to charge, so you can charge old and new ipods with it.
i cant even remember what it was called now, ill try and remember to check the name of it when im in the car and post back
i just bought a cable and my dodge dealer had two part #'s one was for the 3g phone and itouch and the other everything else. he gave me the one for the 3g to use with my 4g and it didn't work so we tried the other one and it workes fine. so they do have two cables and they are different.