Not necessarily. Most in-dash NAV screens sit pretty low in the dash, which is more dangerous than glancing at the watch at eye level (assuming you're holding the steering wheel at the top), but like I said, with automatic voice prompts from the iPhone and haptic feedback provided by the watch, there's no need to look at the screen at all and of course not everyone mounts their iPhone at eye level.
I can't believe you're trying to make the argument for a proper GPS system versus a small screen on your wrist.
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That probably says more about the kind of cars you drive than the market as a whole. And the point an earlier person made is that the device vibrates depending on which direction you're supposed to go, thus the screen size is irrelevant.
Vibrates how? I'm talking cars I enter, not drive. Go ahead and believe a small screen on your wrist is equal or better than a 5" screen on your dashboard.