using iPhone as sat nav?

pigeonpie

can anyone tell me how to do this please and how well it works (in UK and abroad)?
I need a new phone and sat nav just died (again) so thought of getting an iPhone. I have not used one before other than to send a text on a friend's phone so am clueless.

3 other questions: presume it works like a normal GPS and you can switch off data when using it?
I have a Mini - the audio system can sync with an iPhone but not sure if it charges it while in use as I imagine using it as a satnav would run the battery down very quickly?

Last (unrelated) question: are there still issues with unexpected, huge roaming data charges with the 4S? I have heard about people turning off 3G when abroad but the iPhone seeking 3G network coverage when it can't get a wifi signal, so people come home to massive bills etc.
I would like to use my phone on wifi in South Africa and my eyes water at the thought of data roaming costs from there.

thanks for your help

jonkersuk

Yes it works like a normal GPS and I find it works very well for me, you can turn off data when you are using it but there's really no need.

Yes you would need an in car charger to keep it charged whilst you're using it because it does run the battery down quite fast.

I have never had a huge bill when I've used it before abroad, I just turn off data roaming and that's it.

SaLoGo

I use NavFree and never had any huge bills. My data allowance is 100mb a month. The app is free and it does everything I need it to.

Biglad_3

I travel overseas very often and I have a 4S and have never come back to a large bill. Those that do I suspect are either unaware how to turn off roaming or are unaware of how much data an iPhone uses and the cost, even although the network sends a text explaining the cost.

I also use navfree and Skobbler both satnavs are pretty good.