I know I'm being uber optimistic here, but wondered if anybody had come across anything that would allow you to plug a standard(?) external GPS into an iPhone to use with satnav software? Reason: get occassional signal loss but don't want to shell out for something like a TomTom mount when my car already has a GPS receiver built in.

And to further add to my wishlist, I'll want to be able to plug the cable from the head unit into the iPhone as well for charging and playing tunes so some sort of splitter would be required.

Am I just plum crazy thinking that would even work?

If your car has a GPS receiver in it, doesn't it also have its own satnav software?

Does your car's GPS have a data port on it? Does it have BlueTooth? There are replacement BT stacks (jailbeak required) for the iPhone to allow connection to an external BT GPS. Though I've also read that the iDevices now seem to work with BT GPS receivers, so perhaps the replacement stack/app isn't required any longer.

It was a very basic head unit with just turn by turn instructions which I've now replaced with a Pioneer.

The receiver is a simple pin connector which looks very like the connector I had on my old Parrot hands-free kit ... also replaced by abover mentioned Pioneer head unit.

Hmmmm ... thinks ... maybe I could BT the old Parrot to the iPhone ...