Partial wheel skirts - what effects to expect?
 

Hallo,

I have turbodiesel car with Cd of 0,37. I would like to lower that number at least a bit. Therefore I ask for an expertise from you. What aerodynamic options do I have?

- As it is a car with, how we say, a "true blunt end", boat tail or kammback seems a bit impractical to me.
- I have already tried an upper grille block, though just for winter time (insulating my radiator). No measurable effect. (tank to tank measurement, no other options yet)
- The second easiest mod seems to be a partial wheel skirt. I am unable to do a full skirt at the moment, rear wheel sticks out too much.

What do you think? Will that partial skirt improve, or hurt aerodynamics? Can someone guess improvement percentage?

P.S: Any comments are welcome. Do you have any other ideas? (just to be honest: my wife says: the more invisible, the better. Therefore i plan a belly pan for next summer :-).
How about a belly pan and rust? Does the belly pan accumulate road salt through winter?

Why only partial skirts? The upper half of the wheel is moving forward at 2X the speed of the car, so covering more of the wheel will be better. Depending on the car, you might see as much as 5-6% gain? The wheels and the wheel openings are about 20-30% of the overall drag, so smooth wheels are a big part of that.

So far I am unable to secure gap between the skirt and side of the wheel - the wheel sticks out too much. I plan to do full skirt, but it requires far more effort involved (basically it has to bulge out, so the curvature needs to be right and its long run job). Partial cover is just a plane shape, glued to bodywork with adhesive tape.

If you use Coroplast, then you can put a metal rod(s) in the core(s) to hold it in a convex shape.

Seifrob's partial skirts have at least one up side: The wheels should clear them when the car is jacked up, easing replacement.
Paint them and they look good:D

And the upper grille block is great!

MetroMPG gained 2.8% with his skirts

Testing grille blocking & wheel skirts: +5.7% improvement - MetroMPG.com

Go way radical, but make it out of clear acrylic. :)

have you seen our wiki page on wheel skirts?

Rear wheel skirts - EcoModder

Full skirts with aluminum bar structure.
Remove silver wheel covers, exposing black steel wheels.
Paint skirts black to match wheels.

Voila!

Also, start blocking the lower grille, starting with some clear acrylic over the fog lamps.

fog lights are covered, not sure about lower grille - its intercooler intake and i am not sure how much good or bad can cover do.