I like the way you think, but it's a bit more than that, it's also a UX simplified/tested for in-car use.
Interesting thread here that I'm reading right now...
http://www.diymobileaudio.com/forum/...d-units-2.html

I'm just concerned that the N9's unlikely to be supported all that well, but at least there'd be good support for many Android devices.
Still, I'm leaning more towards getting something very basic now, XAV-701BT is just too pricey/sophisticated for my craptastic car.
So far the cheapest offer I've seen is $425AUD (inc post), if I could find a offer for $325AUD (inc. post) or less I'd seriously consider it.

*UPDATE*

Buying this....
http://www.sony.co.uk/product/icd-bluetooth/dsx-a50bt
https://www.jbhifionline.com.au/defa...10180&P=670934
That will do for now...
If anyone feels there's better options for (roughly) that price, please list them.
Later -time permitting- I'll experiment w/a carputer (FOSS/Linux etc) + touchscreen.