As suggested by Metal Micky we place ours on the highly polished walnut dash between the glove box and the switch panel. The support grips just as well there as it does on glass and I find it reasonably easy to see if I need to look at it.

I agree about turn instructions. You will often get an instruction such as "turn left" when the road only veers slightly to the left and there is a goat track that goes straight ahead or to the right that is clearly not the main road.

Peter

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