I think there's already been some slow moves in that direction - I recall the presenters on Top Gear playing with a couple of vaguely similar things, eg. a Lamb

I think there's already been some slow moves in that direction - I recall the presenters on Top Gear playing with a couple of vaguely similar things, eg. a Lamborghini where you could cycle the appearance of the dials (so you could make it look like a "jet fighter" or whatever) and a Skyline that had a screen with heaps of different displays (g-force meter and what have you). Those aren't near a fully programmable tablet but I think that's still a long way off since there might be regulatory problems, eg. maybe you have to be able to see the speedometer at all times. I'm not totally convinced I want a fully programmable display though anyway - I don't think that a million customisable settings would enhance my car. But I'm sure there are people who would like it...