From my experience of built-in sat navs, is that they are overpriced and not as good or easy to use as a cheaper standalone unit. I've even paid out an extra £2,200 in the past to have the touch screen voice controlled one in Range Rover Sport and while is was ok, I've since found my £150 TomTom to be much better at the job. The real advantage is that a TomTom (or the like) is easier and cheaper to keep updated, which is crucial.My recommendation would be to get a decent dash or pillar mount to fit your car from brodit.se and the appropriate mount from them for a TomTom (or the like). Then eitherhard wirethe power or run from the 12V socket. Get the mount right, then it is much easier than having it stuck to the windscreen, much easier to operate and looks almost as good as the built-in or stereo option.
I have a Brodit pillar mount in my Kia Soul for my TomTom. I've also changed the TomTom startup and end screens to Soul pictures. It is in an ideal position for safe operation while driving and it looks good too.