It looks like the exhaust pipe that enters the middle of the silencer. It should be higher, it was damaged or has the high voltage battery have already been repaired. Take a photo from below to see better.
It's normal. It's something the HEV has that the PHEV doesn't. You can actually see it in the 360 renderings in the Build section of Toyota.com. Have a HEV build in one browser window and a PHEV build in another, rotate them to a rear 3/4 view, and then toggle back and forth. The HEV AWD hangs down the most, the HEV FWD is the middle, and the PHEV hangs down the least. I don't know what it is that's sticking down(it's not the exhaust), but I'm severely sunburned and my concentration is crap right now to try and research it. I only knew the stuff above because I happened to notice it a week or two ago when I was checking some other cosmetic differences between models/trims.
Well, I was wrong about it not being exhaust, but it's still normal. I took a look under my car and it's the same.
