My cousin has a Prius 2013 Two. When I took a ride in her car, I was surprised how her ICE sounds. It was a totally steady quiet humming without any "rattling" sound. My 2014 that I bought has a much louder humming sound, above the hum it has a slight rattling sound, like something is spinning. My cousin's car's sound has no such spinning/rattling at all. My cousin's Prius sounds so quiet when driving compared to mine. How does your Prius' ICE sound like? Do you notice any rattling sound at all? I cannot hear any spinning/rattling sound at all in my cousin's Prius. It was a totally steady hum.
Mine is quiet unless I enter the Power Zone. About the only time I hear it is if I am really pushing it. Today I loaded it down with 580 lbs. of limestone from the local home center. I weigh 120 pound, which put the weight at 700 lbs. which is 100 lbs. shy of the limit. I only heard the engine one time when I was trying to get out of the way of a idiot driving a metro bus. No, I don't normally drive my Prius loaded like that. Especially my brand new one I bought and picked up on 3/31 of this year. But the place I got the stuff from quoted $79 for delivery. I could haul the stuff myself for a lot less money and not hurt anything as long as I took my time. This is what I am building. A new flower bed around the big oak tree in my front yard. Every stone was carried in the back end of our Prius. Who needs a pickup truck. I sold mine last year and never looked back. Ron (dorunron) Bed started, two layers of limestone working. Bed completed, two layers of limestone with one layer of caps on top.