230K miles, weirdest noise, my friend said it is normal but never heard it before on other Prius

Sounds normal to me...

 

Sounds like some kind of resonation. Can't say I've ever noticed it in my car, so I'd hesitate to call it normal. But, is it bad? Idk.

 

anything loose underneath?

 

Exhaust noise? Is it the oem cat?

 

Hmmm....hard to know for sure. My first thought was about the transmission....has it been serviced regularly or lately? If not, I'd do that before anything else. (Just a drain and fill on them but use Toyota tranny fluid...I believe the 2011 uses the WS.)

 

Check all the plastic shields. One may be torn and hanging down onto something that is rotating, or it could be just loose and flapping around in the breeze with some periodicity.

If the front is jacked up (securely!), the car turned on, and the front wheels spun at similar RPM does the sound occur?

Are all the windows firmly up? My car can get into a rhythmic sort of huffing sound at around 50 mph when the windows are down part way. (Only observed it a few times, probably analogous to a huge flute.)

 

do the tires have anything stuck in them?

 

Good ideas! Last summer, we had our Tundra and camper out in the mountains and when I would hit 50 mph or more, I'd hear a little thumping noise....I turned off the radio to hear it better and it was on the front/right side. When we stopped for gas, I looked around and the Tundra has a strange little cloth flap inside the front wheelwells covering up the lower part of the engine. The left side came off years ago the the right side was down to just one clip left, so high winds would make it flap. I just removed it....problem solved. (I have looked on Toyota parts sites for replacements and clips but, so far, haven't found them...I think I can live without them.)

 

Yeah. When I post now and it spins for a long time I open another tab and check if the post has made it through, and if yes, close the first window. It cuts way down on double posts.

 

Guessing that method didn’t work for this post.

 

It did not. Checked in the other tab and there was nothing there, so hit post again, and it ended up being a double post. I had waited a good 30s before checking the other tab, maybe I should extend that to 60s.

Or even better, the IT folks maintaining this site could fix whatever it is that is taking so long for posts to post and report back to the user's browser!

 

I hit refresh (F5 on a pc), the little semi-circular arrow at right end of address field in Safari on iPhone) a boatload of times, after the little (never successful) "working" symbol quits moving. Sometimes that works, sometimes not. If not, wait a bit longer, cross fingers, hit "post reply" one more time.