I offered 3 potential solutions that work across ever model (unlisted) and you guys are downvoting?

• USB - apple 30 pin: note that the pin number might change depending on release year. Someone smarter than me will mention why firmware might not work out.
• USB to aux: this will give you a headphone jack and is the most reliable
• FM transmitter: if you lack a headphone jack you can also get an FM transmitter. It makes your device a mini radio station. These are pretty unreliable or staticy, but sometimes you need an option. I would recommend a new player first.

We used FM transmitters for those guys back in the day. Plug it in the headphone port and tune the stations.

There are 3.5mm (headphones) to Bluetooth adapters. If you car are Bluetooth u can use this.. fairly inexpensive. And if you have FM radio in your car there is 3.5mm to FM adapters..basically you have a mini radio station with short range but enough for your car to pick it up

It is likely the car USB port is looking through directories for MP3 files, and thats not now those iPods present themselves when hooked up via USB. You might be able to find an audio-to-bluetooth adapter, but it is likely you will not be able to control the device through the car's interface, so you would have to press play manually.

(Side note: older cars with USB might have a very low-level relationship with the USB sticks, where they read files in the order they were written to the device, without regard to what folders you put them in. There are utilities that can reorder the files' physical position on the stick so that albums play in order)

Can you just get an aux cable and plug that in?

I've had one of those (battery died, unfortunately) and if you'd look at its files, you'd notice that they are organized in a different structure than what an MP3 player might expect.

iPod_Control\Music's sudirectories might contain some songs, but the filenames are hashes (corresponding to the entry in the iPod db). The metadata and the contents are perfectly fine, and you can play the file yourself via a different player (you can probably test it in your computer).

I suggest you just connect the iPod through the 3.5mm output audio jack or find a 3.5mm audio output to Bluetooth transmitter adapter.

EDIT:

WTF. I triple posted. My bad. I deleted the two others, also corrected some minor typos and mistakes.

Seperate from the FM transmitters that other people have mentioned, you can install an FM modulator into your car. This is a box that goes behind your stereo, feeds power off the stereo power supply, and connects directly to the antenna wire to supply the frequency modulated sound signal directly to the antenna without traveling through the air. Similar to an FM transmitter, it has a headphone wire that plugs into the headphone outlet of your ipod for the audio signal. It can bypass the interference problem that FM transmitters run into, but the one I installed back in the day actually picked up engine revving noise from my alternator, so maybe it needed better wire shielding. Obviously this requires taking out your stereo and doing some wiring work so you need some tinkering skills or have it installed by a pro.

The reason the USB plug on your ipod doesn't work is that earlier audio devices like the original ipod didn't have a way to transmit audio digitally over USB, it was only used for charging and file transfer.

Further to the other answers; I have one of these for using my iPod in the car. It has the added bonus of taking line-level volume, so you set the volume from the head unit, not the iPod. And it can charge while you're using it.

I think it'll charge from the head unit's USB socket without trying to connect, because the USB plug is just for charging.