Carpet in the trunk area may look nice when buying your car but I feel it is not practical. I purchashed a package of four black 24"x24" fatigue mats from Walmart for $10.00. The mats go together like a puzzle so I took the main carpet out and used it as a temp plate and cut the new liner. I then flipped it over and duct taped it at the seams. Then I popped out the little side storage cover and frictioned fitted a piece to cover it.. It looks great, is washable and a great price.........
The carpet in the hatch area of our 2006 still looks great after 34,000 miles. I suppose it all depends on how you use your Prius. Do you transport dead bodies in the back of yours? Tom
Bought a weathertech trunk liner on Amazon for $65 no tax, free shipping. Price has gone up to $69 but still a deal: http://www.amazon.com/dp/product/B000KVDVSC?tag=priuschatcom-20
ive handwashed and machine washed those $199 toyota floor mats with no ill effects. i only washed the floor mats twice, and hand washed the cargo area floor mat once. because of the agitator, i just wash one floor mat at a time with a full tank of water and a couple towels. and then hang them to dry
Another option is to turn the carpet over and the black rubber side is up. Great for me as I can throw my clubs in and shoes and not worry about getting the carpet dirty. No cost as the mats were already there.
A third (or is it 6th) option is the rear carpet avilible from Sigma automotive. Not only does it keep the carpet clean, but as it also covers the back of the rear seats, it keeps all the trunk space clean!!
I bought the clear trunk mat here from the Prius Chat Shop. I like it very much. Easy to clean and still shows the gray carpet since it's clear.
Personally, I don't quite understand the point of getting a second protector to protect the first protector (the removable trunk carpet) that protects the already carpeted trunk floor. Although it's not the equivalent, it's not unlike people getting another plastic slipcover to protect the plastic slipcover that's protecting the sofa upholstery.
Not all Priuses come with the trunk mat. Mine didn't and it sounds like the OP's didn't either. I made my own protector with anti-slip material duct-taped together, but the tape melted in the summer heat. I think I'll ask Santa for the WeatherTech for Christmas. That carpet is a dog hair magnet, and I hate having things slide around back there while I'm driving. The clear mat looks like things would still slide around on it.
I thought OP had it -- OP mentions taking the carpet out and using it as a template for the protector OP was fashioning.