When I was in the market for a windshield there's one main company that sticks out... Rycote.
Now this windshield is used by me for recording SFX (spot fx, and ambiences) with a ME66 Sennheiser... So I can't verify that it cuts out 80mph wind blasts at the top of a hill recording an interview but for me it gives clean SFX even in windy conditions.
It is slightly expensive but in my opinion it's a price worth paying; nothing worse than getting back to the studio and realising a great sound effect has been ruined by wind which you mightn't have heard upon recording.