I have previously been using a Kenu Airframe for a phone mount. It is very easy to use and works quite well. For most phones it holds it great, especially when the phone's volume and power buttons arent directly on the side of the phone where the mount would clip onto it.
Unfortunately with my Nexus 6 the buttons are right on the middle and the phone has to be held slightly offset. The Kenu mount rotates but does not have enough resistance to securely hold the heavy 6" phone.
Despite this, the mount still holds the phone securely even on track days, but the mount still moves a bit especially when you have the tug of a charging cable plugged in.
I really just wanted a mount that would clip onto the dash somehow, but options are limited. In the end I found a vent clip which is a great solution:
http://www.dsldevelopments.com/brodi...81-E82-E87-E88
It wasn't particularly cheap but arrived just in time for my Tasmania trip. I drilled a hole in the middle and mounted a ball swivel mount (cheapo ebay thing) with a screw.
The mount is very strong and can be oriented towards the driver. The last pic shows my old Samsung Galaxy S3 mounted (not my Nexus 6)