Attention Winter Wagon Drivers
 

Just finished a road trip through the Rocky Mountains with some periods of heavy snowfall. Found the rear liftgate accumulated a thick crust of 4" compacted snow which completely obscured taillights, window, everything. Had to clear it off several times. On other occasions, with wet slushy snow, the back gets very dirty and even the rear wiper can't keep up. I know this is due to wagon aerodynamics and recall from the old days that some manufacturers installed a rooftop deflector to direct air downwards onto the liftgate which did a much better job of keeping the back clean. Others used side deflectors, and I'm sure most wagon lovers are familiar with this. Does anyone know of a suitable air deflector for the S212? Must have vents to direct airflow down and across the back. As I can only find roof spoilers/wings on the 'net, I'm hoping those in similar winter climates, including Europe, can chime in with some leads.

BTW, the 4MATIC absolutely rocks! Although other traffic was at a crawl on the highway, many even with their 4-way flashers going, I was able to comfortably cruise without drama.

This is what I'm talkin 'bout
 

https://cimg4.ibsrv.net/gimg/www.mbw...fc89f924ad.jpg
https://cimg6.ibsrv.net/gimg/www.mbw...93854432dc.jpg

Wagon Love
 

Funny how love for wagons changes with markets. In Europe they outnumber SUV's, but in NA they aren't very popular. I still like to sneak a look back at the S212 while walking away....

https://cimg5.ibsrv.net/gimg/www.mbw...9eb2892380.jpg

Bring those 50 mpg diesel wagons to US and see how the Explorers will sit on dealer's lots. ;)
Your wagon does have factory wing on it and knowing a little bit about aerodynamics, not all the air deflectors work as you hope they would.
I did own W210 and W211 wagons and did not have such problems.
What I am getting to is that questionable deflector can do more bad than good and considering how rare the condition happens in life, I would not try to add elements that factory found not necessary.
Just carry more washer fluid with you.

didn't know canada had pre 2018 e400 wagons. jealous.

Yeah, and this year we have the C300 4matic wagon starting at Cdn $46k (about US $37k at today's rates). I was at the dealership this am to pick-up the rear sill protector (A253-693-20-00) and had a look at the newest S213 E400 wagon in black with brown leather interior. Very nice with a base price of Cdn $74k (US $60k) but they managed to bump the content to $86K. I'd only be tempted if they bring the E43 4matic wagon which, if the price difference between the E400 sedan and wagon holds, should also come in at $86k (US $70k).

Can't see any of the photos (wonder why? Admins?) but I can visualize what you're describing. Back at the turn of the century I owned a first-generation Subaru Forester that had the same problem. I traded it in on a second-generation Forester that had a small rear wing that acted as a deflector. It kept the rear window freer of snow, rain and spray but wasn't completely effective. The wing was much larger proportionately than the small lip on our S212s that houses the CHMSL.

Must be something at your end as the pics appear for me? I think MB would avoid this solution because it also causes drag which lowers fuel economy. As we've learned, CAFE dominates the engineers minds to the point they are/were willing to cheat.

This
I tried an aftermarket spoiler for my previous wagon, an Audi Avant to try to help avoid the same problems OP describes...
Result? Not much better. I mean, very slightly better, but not really worth it. However it did look pretty nice!

I will say the Mercedes rear wiper is WAY better than my previous wagon. It actually cleans the rear window instead of just going thru the motions pretending to do the job