Really just looking for ideas and maybe some pics on how you have set that up on your cars.
I don't want one of those "suck-to-screen"-thingis as they are ugly and as I would prefer the phone/satnav to be more near the dash. I had bought one of these cheap holders and it came with a suck-on-plate that I did stick on top of the dash - but it is too flimsy and moves easily thus not keeping the phone in place.
A mate of mine did recommend that: http://www.dashmount.co.uk/index.php/Dashmount-Brackets/Mazda.html
It even lists a version for a MX3 but unfortunately no picture :(
But maybe you have even better ideas :)