Will 12v dock w/lightning adapter charge iP5?

I have an older ipod dock that hooks up to my car stereo with audio and charging capability. It won't charge a iPhone 4 or 4S because it uses the old 12v firewire wiring/charging. If I purchase something called a Scosche Passport or a generic 12v to 5v adapter that should fix the problem. However, I just purchased an iPhone 5 and was wondering if I still need a 12v to 5v adapter in addition to a new 30pin to lightning adapter. I was wondering if the new 30 Pin to Lightning would convert the old 12v firewire to work with lightning. If so, I wouldn't need yet another accessory to make things work.

Please let me know if anyone has an answer for me. Worst case scenario: I go to Target and buy a 30-L Adapter and then return it.

Thanks,

Josh