Reducing Drag with bumper shape
 

Hello everyone, I saw that many cars' front wheel is a little direct to the front wind because of the bumper shape. I did some simple changes to my car 3d file. And I want to reduce drag on the front and back of the car. Did I do it right. Does it work? or what should I do to make it better?

better
 

I think the front mods would show an overall drag reduction even though they add a bit of frontal area.
With respect to the rear,I think you could do some gentle plan-view taper,vectoring flow into the wake,as well as some pressure recovery.
Here's some things I've had success with and am in pursuit of:
http://i1271.photobucket.com/albums/...d2/Scan1-3.jpg
http://i1271.photobucket.com/albums/...d2/Scan101.jpg
http://i1271.photobucket.com/albums/...d2/Scan102.jpg
http://i1271.photobucket.com/albums/...d2/Scan2-2.jpg

yes. before you do anything, get the template designed.

"yes. before you do anything, get the template designed."

Is this what you mean?

If your model is of the car I think it is, it's a beautiful design, one I would be weary of altering the exterior significantly.

2009 Alfa Romeo 159
2009 Alfa Romeo 159 1750 TBi specifications, information, data, photos 195701
That coefficient of drag above almost as good as traditionally one of the most aerodynamic cars sold - see below.

1997 Porsche 911
50 Years of the Porsche 911
In my opinion the traditional route in this forum of doing front grille blocks and under belly pans is the way you should go.

Perhaps the wide sporty tires the Alfa Romeo 159 runs could be substituted with something narrower to reduce the frontal area, and less sticky to improve mpg.

Thanks, I did a lower grill block already. We have a middle and lower grill opening. So I block all the lower part. And the middle is enough for the cooling, and directly open to radiator. Also, I have Vortex generator at the back. nothing more. I did a air dam 3 months ago, but the car is low, and the parking was a torture for me. So I cancel the dam. Now I've got a 3mm clear plastic for wheel cover. And I reduce the wheel area from 245mm to 225mm. I'm waiting the summer holiday for underbelly, back wheel arch cover, and more.
Also I will copy the CLA front bumper design for the car. vertical Air duct for the wheel I mean.

To be fair, the 911 has 295 tires stock and massive rear fenders, which can't be good for the Cd.

I admit to being a fan of the ol' neun-elfer, but that is a real stretch to call it "one of the most aerodynamic cars sold". There are plenty out there with far better Cd--from the Prius, to the DS (ooh, a rhyme!) to the Citroen SM, to at least a couple of Benzes, the 1st-generation Insight, and on and on. 0.30 is decent, but unspectacular by today's standings.


Anyway, back to the OP's question:

You might try some deflectors under the car to push the air out around the tires, and some "mini boat tails" behind the tires to get the air flowing nicely again after the tires have disturbed it. Basjoos over at Aerocivic - Honda Civic modifications for maximum gas mileage - aerocivic.com has examples of those.

-soD

"mini boat tails","underbelly" are one of my favorite mods, because ıt is nearly visible from outside. Also at the attachments you will see one of my purposes of the new front bumper. Anyway, so if I push the air out around the tires it is good. And Also I think it does not change frontal area of the car.

PS: I wish I could do a mirror delete or Camera mod to the car. But the autofocus makes it worse, I tried my android phone, at night it is not good.

PS: Also we have an idea of new fender, for the car. New Molds.jpg what do you think, is it good for the reducing drag? or worthless to do it?

Yes,that's the idea.
The 'Aerodynamic Streamlining Template - online tool ,4th line down from top of Forum page will allow a proper overlay.
For the plan-view taper I'd recommend Fachsenfeld's contour:
http://i1271.photobucket.com/albums/.../11x17Scan.jpg