Uh, Apple does make an adapter for it... I know it's $30, but it's at least a solution. (Our car has a USB port, so it's just a matter of changing the cable for us.)
Except that unlike the old cable, with the adapter it doesn't provide a charge, only the connection. So it drains the battery as it's used, then I have to charge it by connecting it to the car charger. There doesn't seem to be a way to connect it to the stereo and charger at the same time, at least with the adapter.
Really renders the whole thing useless. The cheapest fix is to return this iPod, and buy an iPod classic for about $250. Way more capacity than I need, and more money than I wanted to spend, but it does have the 30-pin connector like my old (!!) 5th gen, so hopefully it would work the same...