Don't know whether this was discussed before... but:

GPS screens seem to be very resilient to sunlight, and are perfectly readable outdoors where the cars are normally driven :)

Some GPS devices play audio and video content.

So.

Are there any high-resolution GPS devices with HDMI input?

With built-in battery and light weight, that would be an ideal monitor for Canon 7D, SI-2K, and just about any other video capturing device out there...

Sorry but I would think most GPS would be rubbish in almost every area - very low res screens imposable for critical focus not to mention colour and forget about judging exposure to any usable degree.

Not sure where you drive or what you drive but here most cars have tinted windows to some extent and a roof meaning lots of sunlight is cut back to begin with.

But if anyone knows any different happy to be proven wrong.