Got one of these after giving up on cheap versions. This works!
In car essential
The TuneBase FM lets you play music from your iPhone or iPod through your car stereo, whilst simultaneously charging your device. Ensure your tunes sound crystal clear with ClearScan, which automatically searches for the best frequency. TuneBase FM will effortlessly let you switch from playing your music to taking calls hands-free through your car stereo. The cradle will fit any iPhone or iPod and is adjustable for ease of use