Don't use Raybans or Serengetis unless you drive a Porsche. They are glass. Pilots flying aeroplanes should only wear polycarbonates. (my opinion of course). Actually it's a wonder anything else is not illegal.
If you're gonna smack the dash hard enough to be worried about your sunnies breaking, it
probably won't matter anymore.
Be aware photo chromatic lenses aren't instant. Passing through cloud shadows the consideration.
Polaroids definite no no.
LCD displays can become unreadable (any sunglasses retailer worth their salt will know this if you mention flying) and while great for spotting fish and golf balls through water, you won't be able to pick wind direction from the water surface.