Are there rear fender liners?

No, there are no liners in the rear.

I have spent a good bit of time cleaning out a lot of mud and muck from the rear wheel wells. I try to keep up with it when washing the car.

 

Yeah, I don't ever remember reading about someone on here with a problem in that area of the car. Also just confirmed what you're saying; there's no proper splash guard / liner assembly as a part, which I suspect is handled by the frame design of the car, as well as a bunch of other small parts.

 

I live on a dirt road with a rock driveway not a lot of mud but I'm in a lot of mud out on people's fence and tree lines on their property pretty regularly The best thing I found even better than my pressure washer which I have to hook up and turn on and all that is the gold nozzle with the three ball bearings in it from home Depot it's blister packed It goes on the end of your garden hose that thing will blast all the mud and crap out of the wheel wells and all areas of the Prius very quickly and you can adjust it on the fly from a straight stream to a fan spray it puts all that red clay right on the rocks immediately I try to keep up with it throughout the year because this red clay will get into your chassis and stay there for years if you're not careful it'll get in between bushings and everything make stuff squeak and groan . My garden hose is right where I park always at the ready If I get out of the car I have to walk right by it so I might as well turn it on and spray out the wheel wells and whatnot even in the winter. But in the rear there are no fender liners It's pretty smooth back there what gets caught in the rear wheel wells is that the trailing and leading edges of the well .