Remember the Boy Racers boot mounted wings?

Well all I want is a deflector to break the "vacuum"

and direct air down over the rear window to stop

it accumulating crud.

Superskoda do one.....

http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R

I'm sure there was a member who had fitted one, and I think found it made no difference, which is logical as the space immediately behind the car is a low pressure area so any spray from the rear wheels will automatticaly get drawn into it.

I think Graham's comments are correct and unfortunately nothing can keep the back end clear of road muck. It is the one downfall of the flat high back, but it more than makes up for the stuff you can shove in there without fouling the roof. The cars sides are not much better, it can be washed and within five miles just as dirty again. The mud flaps do not make the slightest difference to this. I have had many cars over the years and can honestly say the Yeti is one of the hardest cars to keep looking clean.

I looked at that one http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R

it needs to be a wing type to redirect the airflow down. I shall have to make one

Even a wing type will not reduce the low pressure area behind the car. For that you would need a complete redesign of the whole vehicle. It isn't just the roof shape that affects this but the whole shape, including the way the air exits from underneath and the way the air comes of the sides!

This might make interesting reading for you:

http://en.wikipedia.org/wiki/Kammback

I have previously owned three flat backed cars that had factory roof spoilers, Mitsubishi, Mazda and Daihatsu, they were not solid spoilers and had a small gap between the roof and the spoiler underside. This caused some air to flow under the spoiler and over the rear screen. They kept the rear screen very clean.

Honda Accord estate had a fantastic rear wing design, it was very subtle to look at but when it rained the rear of the car stayed dry, even the rear wiper was not needed, maybe a look at the wing on a Honda will lead to somebody making a similar aftermarket design for other cars.

 

 Personally, I do not use the rear wiper or worry too much about the dirty rear of the Yeti, I have wing mirrors and can see adequately behind.

If the flat back and general shape of the Yeti helps improve fuel economy then I for one can live with the extra dirt and the need for regular washing.

I looked at that one http://www.superskoda.com/Skoda/Yeti/Skoda-Yeti-roof-spoiler-SPORTIVE-by-KI-R

it needs to be a wing type to redirect the airflow down. I shall have to make one

Something like this:

Actually, the rear hatch is intentionally designed so that air flow detaches from it, killing unwanted lift and inherent drag.

Edited 18 February, 201412 yr by briskycat