I've only experienced one back in 2006 in a C6 Corvette and that one was positioned so far down towards the bottom of the windshield it was hardly any better at keeping my eyes on the road than just using the IP.
Absolutely love the one in my GMC Acadia. Very non obtrusive. Makes me want one for every car I will own in the future. Not just for MPH and cruise control stuff, it also shows me the name of the song playing when the song initially starts.
I've had my ZR1 for over 3 years now and find it very useful. Sadly, I have to really concentrate on using it as I have 45 years of habit to overcome. For stovt001:position on the windshield is adjustable, so you can raise it as desired.
Comments
Way back in 2005 they even integrated the radio information (channel, song, volume) in addition to the Nav system instructions (left arrow 1.3 Miles).
Every car should have this feature.