Audi a6 e tron Cd 0.21
 

https://youtu.be/ikZAsnplfUY?si=EARBYFTh5PFVknhU

Not bad, cannot wait to see this at local dealer

I like it!

' 0.21 '
 

I'd like to know what the 3rd decimal point is.
It could be Cd 0.210, Cd 0.219, or somewhere in between.
Tesla and Hyundai provided this data.

I got a answer in Linkedin that its 0,210 so 0 is the last number.

Also underside is different in these a6 variants, if you put other cars underside to the other a6 model difference in drag is at least 0,02 Matteo Ghelfi commented on linkedin.
https://media.licdn.com/dms/image/v2...vRBET0TDt6Ik6w

https://media.licdn.com/dms/image/v2...tKD6x_Tj6QvT_o
That just points out that the deflectors have huge impact on drag. And I think they are not using the best shaped deflectors which should be D style. That downward sloped deflector will still direct air to the tire which is like a shredder and will create turbulence.

More pictures in linkedin link

https://www.linkedin.com/posts/matte...member_desktop

I feel like 3D printed TPU wheel deflectors are the perfect solution. Flexible, easily printed into custom or complex shapes, can be infilled, colors, etc.

Propably 3 d printed TPU covers would be good for many drivers. I usually test using 3mm thick abs plastic the shapes and later then try to think what material is best to make more permanent prototypes.

black rubber sheets or clear pvc sheets is my latest choices.

Any examples for D style? Compared to others? TIA

I tested them in my ID3. More testing will come in the Model y.

https://scontent-dus1-1.xx.fbcdn.net...Zg&oe=66EEBD9C

Bottom should be also closed.

In almost all race cars they try to cover the tires side with the front bumber. They dont need to think how badly people drive over the curbs and brake the bumber...

Most of these spats are not coming to the outer edge. If its flat plate it might be best choice but more you try to make smooth shapes more towards outer edge you should bring the deflectors. Same problem as with trucks roof spoilers. Easy to direct air too steep on the roof...

I see thing like the tire is a shredder where all air must directed away as much as possible. Think about cars underside and front bumbers.

If you are driving old american car with dirty underside, its better to have a front air dam than smooth round front bumber. Same principle for the tires is what I recommend.

I know some low drag solar racers dont have such a shape, but its still D shape and the tires are much narrower and usually round like bicycle tires. So its not exatly the same situation. Meaning they do direct air to center of the tire.

If directing air around the tires makes a big diff, I’m wondering how much of an impact actually lowing a car by an inch could make

Would depend on how the airflow changes. You would be reducing square plate equivalent a small amount, but compressing flow underneath much more