I went with weathertech mats and I couldn't be happier.The OEM ones don't look like they'd be very effective with real world winter use. We plan to order some WeatherTech ones, since they cover the sides a little more and would be better at containing water. Though from the looks of it, the WeatherTech rear mats are also pretty much flat.
The OEM weather mats that came with my OR have a center piece for the back seats that connects to the right and left sides and does cover the transmission tunnel. You might have to order that separately? Or perhaps it's just a special thing with the OceanRace.I drive for Uber, so you can imagine the abuse these things get. I did consider the weather techs, but concluded that they were too overpriced for what they were. Also, they're a bit too rigid. This means they must be tipped at a steep angle to get into/out of place. Not ideal when you have some rancid liquid you'd really like to keep inside the mat during removal. It is worth noting that the weather techs do cover the carpet on the transmission tunnel, whereas the OEM ones do NOT. Again, this would make removal more difficult and decided the weather techs weren't for me. For less than half the price (under $150), I went to my friendly local Volvo dealer's parts department and picked up a set of OEM all weather mats. I'm satisfied with them. First of all, the rubber is THICK, but it's also very bendy. I can fold the corners in during removal to keep the debris in the mats. I throw them on the ground and take a hose to them. For stains, I use soapy water and a sponge, then the hose. Air dry for 10 minutes, then back in the car.