Have you considered the Brodit holder solution?
Have a look (link below) or drop me a message and I will be happy to advise (Wizard listed either as Xda Minis or MDA vario)
you have the choice of passive holders, active holders charged by cig lighter or permanent fixed power version also for hidden cables etc. All attach onto a proclip mount that is specific to your vehicle, in a variety of positions on your dashboard.
Hope that helps,
To view and buy all Xda Brodit cradles and proclips, visit my site www.dsldevelopments.com