Wagon rear = dust magnet

[wfdTamar]

Jeez, the back of these wagons attracts dust like crazy. The slightest bit of dirt road and it's all over the back window. I've had lots of station wagons and never had this problem. Is it the sloping window? I think I'd prefer a more conventional shape rear (also to get back more useful shaped inside space) like they had on the Octavia I.

[Inego]

My two civics, GolfIV, Outback and Octavia have attracted dirt to the rear window in a similar manner - seems pretty normal to me.

[K1W1]

I've had lots of station wagons and never had this problem.

I find that surprising. What are some of the other wagons that do not have dust problems on the back window. I have never found one yet that doesn't.

[Hillbilly]

Its caused by the way the air rolls back after passing over the roof similar to the action of air across an aircraft wing

Back years ago people used to fit a diffuser ( for want of a better word) that directed air down across the rear and it seemed to help a bit.

May depend on how often you clean it as to how obvious it becomes. LOL


Also a very good reason why you shouldnt travel with the taildoor up or the window open as it will suck the exhaust fumes into the car with sometimes dire results.

[candy_wagon]

Every car I have had has been a hatch or wagon and all have suffered the same problem.

Yes it's annoying and the first thing that makes me think "jeez, car needs a bath!" but at least we have a back wiper to give us some clear view.

If it's just dry dust I generally just blow it down with an air compressor or lightly fan it off (for want of a better word) with a towel.

[Martin]

My Mazda 3 seems to be worse in this respect than my Octavia wagon

[K1W1]

This is not the best picture in the world but it should explain things (I hope)



On a car shape there is a vortex created in that area behind the taillights. As the car moves forward the air in that area actually rotates clockwise in this case and sucks the road grime from behind the car and the air coming under the car back up onto the rear of the vehicle. On a car shape this is the obviously the taillight area of a wagon shape this is the whole rear of the vehicle. As mentioned above driving a wagon with the tailgate or rear window open is a really bad idea.
For those interested in racing this is the area you need to get into to get a tow or draft the vehicle in front. If you can get into this area you can actually feel your vehicle being sucked forward into the rear of the vehicle in front (don't try it on the road please).

[Swampy]

The vertical lip at the top of the tailgate certainly doesn't help, as it stalls the air against the rear glass. Polish the rear window with Rainex and the dust build-up is reduced as it can't 'grip' onto the glass as well.

[wai]

It is nothing more than a result of vehicle design. There is an area of lower pressure that bubbles along behind the car.

In the past various "tricks" have been used. For those old enough, you will remember the roof line deflectors fitted to station wagons to direct air over the rear windscreen. Mercedes Benz even re-designed their tail light lenses with deep grooves because they found the smooth tail light lenses were dirtying up too easily.

Now the solution to rear visibility is a wiper on the rear windscreen. Of course it does not do anything for dirt on the rest of the rear of the vehicle.

[wai]

The vertical lip at the top of the tailgate certainly doesn't help, as it stalls the air against the rear glass. Polish the rear window with Rainex and the dust build-up is reduced as it can't 'grip' onto the glass as well.

That's right. A little spoiler on the rear will actually make it a little worse. You need a downward deflector to cause an air flow across the back of the vehicle and move the lower pressure bubble away from the vehicle.