That's what annoyed me with the other nav system I had in my Z, but that's now in the bin due to numerous reasons.....
Those screens you're thinking of are the resistive type and feel like pressing your finger into a piece of cling film and look a silvery/grey colour in sunlight.
I'm looking for a unit that uses a capacitive screen which is similar to what's used on iPhones/iPads and should produce nice blacks even in sun light, but no LCD will look perfect in direct uber sunlight. These also allow multi gesture use so you can pinch to zoom etc. These screens look and feel a bit like glass or clear, solid plastic.
The problem is that these units cost £££'s and will make the final price closer to £400 than £300, but bulk buying will hopefully make it a little better.
As for speed I'm looking for a minimum of 800mhz/256mb ram which should be pokey enough to run sat software/mp3/mp4. I'm looking forward to be able to use google maps with traffic update, use the web and stream music directly from http://www.di.fm over my MiFi dongle as I have a 15gb limit!
As for turning on when the car does, that will just be simple electronics from the temporary live. I'll have a think about that when I've got a unit. Thinking telecoms relay's or 555 timer to make sure it's a timed click. (not press and hold, which will probably reset it or something) not thought about it too much yet.
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