Buffeting turbulance inside the car.

This has happened on every car I have owned, to varying degrees, especially above 40 mph. It seems the more aerodynamic the car is, the worse the 'effect".

Wait, it may not have happened on my '67 Chrysler Newport... But I wouldn't exactly call that car aerodynamic....

 

It happens with any of the newer cars with good aerodynamics. With older cars and trucks there is so much external turbulence that an open window doesn't make much difference. If you want to drive your Prius with an open driver window, experiment with also opening one or both rear windows a bit. You should be able to find a combination that will eliminate most of the buffet.

Tom

 

I find having all the windows all the way up seems to eliminate this noise. I use the AC over 70km/h and weather permitting I have window down under 70km/h. Saves your ears.

My dad went deaf from driving on country roads with the window down. Dad was a truck driver and delivered newspapers by throwing them out the window into people's driveways along the highway.

 

I think maybe those plastic covers for the edge of the windows may help with this, not sure because I have never had any

 

We had the same thing with our 2007 Prius, so we installed the Window Deflectors, which helps. Doesn't eliminate, but it helps.

You get better MPG if you have the windows UP and the AC on over ~45 mph, anyway.

 

ya i drive with the back windows down because that thumping sound make me fantasize that i got a 1500 watt sub woofer in the hatch

 

happens to every sedan I've owned, open the window behind it a couple inches - benefit, you won't get a face full of wind, either

 

We have a Kia sedona van and one time while driving on the highway the kids ran the rear window down and I literally could not hear them screaming... it was soooo loud.

I have not tried this in the Prius.

 

That would have been something special to see.

 

The idea behind those is to induce turbulence in the airflow outside of the windows, which isn't something most Prius drivers want to do since it will increase drag. This is why the moonroof has a pop up strip at the front: it deflects the airflow up and away from the opening, but only when the moonroof is in use.

What happens in a streamlined vehicle like the Prius is that an open window acts like the mouth hole on a flute. Air blows over it, inducing a tone. Being a very large flute, the tone is very, very low: "whup whup whup whup..."

Tom

 

This is the same phenomenon as blowing over a coke bottle or any cavity with an opening over which air flows tangentially. When you blow over the coke bottle, it hums an audible sound and its note is dependent on how much fluid is in the bottle, or more accurately the size of the cavity. The harder you blow, the louder the sound is but the tone remains the same. The larger (emptier the cavity) the lower the note. The Prius passenger cabin is large so its tone is below the 20 or 30 Hz limit of human ears. Its frequency seems to be in the 2 Hz range and I noticed it in the Gen II as well as the new Gen III. Breaking up the airflow over the cavity may help (it usually does with sun roofs equipped with a flap). So the aftermarket window inserts might help or might not depending on how they break up the tangential flow over the whole window opening. But there will be a slight increase in aerodynamic drag and MPG but doubt that it will be noticeable. Will be curious to read if anyone tries it.

As a side note, I find that opening the opposite window seems to cut down the volume below noticeable levels. (By opposite, I mean the rear passenger window with the front driver window for example). Other combinations might work too, just haven't tried. Adjusting how far down each window is rolled then gives the venting desired versus the wind noise and buffet.