Digital to mechanical interfaces. Brrr. Not that easy in a small, cheap package. Also needs decent feedback to the electronics to ensure the mechanicals are indicating what the electronics tell them to do.Well, again not even e-ink, tho it's closer I guess. I'm talking make a traditional gauge but use some kind of servo, or microstepper motor to move your dial or indicators physically, in the real world. Like a CNC machine ya know? It's more work but the result is something that again should be indistinguishable from a real gauge. You should be able to outfit a P51 with these and someone would think "this looks original" and then you reveal the secret plot twist that they've been flying evil digital the whole time! Muwahahahahahaha *moustache twirl*
Certainly realize this sort of thing is done with stuff like CNC, but now we're talking lightweight, long-term vibration, life-critical stuff. Steam gauges are probably the better implementation.
As for as E-Ink, I love my Kindle, but the stuff isn't fast.