I notice sound at 75mph in the Prius rather than 65mph, but what's striking about the sound is 2 things:

1) The gas engine is so quiet, that's NORMALLY what I'd hear in a car at that speed, so

2) The silence makes any wind sound a little bit eery and

3) The "shape?" of the sound is different from most cars - it's more or less from all around me rather than a few spots (I assume because of the aerodynamics of the Prius).

Sometimes that wind sound freaks me out a little bit, but I'm still confident that it seems loud not because there's a lot of wind, but because I can't hear the gas engine at all and normally that would cover up the sound of air rushing by.

I have also noticed that a good waxing at the car wash reduces the volume of the sound... driving with a dirty car increases it.

Prius 2006, bought September 14:

Well the fluttering wind sound I hear is not all around me. It is most clearly from the front side windows.

I'm not sure what other cars you have driven but with most of mine, I would not hear this wind noise, even if they had a quiet engine. In fact, most other vehicle engines make less noise than the Prius at freeway speeds. As I said before, this is because bigger engines have to work less at higher speeds. At the same speed they use less RPM's than smaller engines like the Prius. Less RPM's equals less noise.

I may order a set of those wind deflector shields. If they do eliminate the wind noise then that will tell me the Prius doesn't have a very good window seal.

I came here hoping for a fix. C'est la life.

Anyway, I hear this whistling sound too. To me it sounds like it's coming from the outside rear view mirror--maybe the wind going through the crack where the mirror housing rotates if someone clumsy (like me) bumps it. You think?

Wow, the thread is over a year old.

I still have the wind noise and it is not coming from the outside mirror. Most definately from the window seal.