I have a 2014 Prius v that I bought new in January 2014. I've had this persistant rattle which seemed like it was coming from the back seat behind the driver. I've taken the rear seat partially apart and glued and shimmed things to no avail. I've emptied the entire contents of the rear storage area and it still rattled on. Anyhow I've had this !!!#@#* rattle for six months now and think I finally found it so I'm telling you guys what it is so it may help if you have the same problem. Turns out the noise is coming from under the car just ahead of the rear tire where some body type plastic which juts down about 2". This piece rattles when against the frame just ahead of where one would put a jack for lifting the car. I've temporarily stuffed some old paper napkins, which were handy, between the plastic piece and the frame. Noise is gone! I'll eventually remove the napkins and then load up the area with silicone. I'm doing both sides of the car just in case.
Was this a constant rattle that you had, or was it only at certain times? I've got a rattle that I hear only when on a slight incline, and giving the car a little gas, so the engine is working but struggling a little. The sound seems to come from behind the dash around the glove area. I've emptied the glove box, and felt if the vibration rattle was the glove box and it was not. I wonder if this could be a warranty claim for me? A friend in my car also said he heard a rattle in the passenger back seat.
Rattle,rattle---rattle,rattle!!! Prius....Prius.....Prius... Some of the owners have used peel and stick felt to deaden the more offending noise sources. I'm old enough to have tinnitus, so even though the creaks and squeaks on my '10 are at a lower frequency than the background ringing, I just deal with it by concentrating on whatever podcast I happen to be listening to. The Prius isn't the creakiest car I've ever driven. I had a 92 Geo Metro Xfi that was (a little) worse, but my hearing was a little sharper 22 years ago.
I thought it might be the rear seat belts. There is a plastic "clip" you slide the belt behind and insert the metal latch into the hole for that....
