Several Ideas
 

I started looking at the under body and it is all packaged pretty tight, everything is packed up inside the frame rails,
it has a pretty slick pan under the engine with a single hole (oil access),
looks pretty easy to do the under pan but wondering how much gain it will be worth considering the current packaging.

Came up with ideas also for dams for the front/rear tires as well as skirts, partial grill block (from the sides). Also looking at alternative mirrors besides the interior style.

Looking forward to getting started just need to find time.

What car are you driving? seems like the bottom is pretty nice, tire dams are a nice feature, but i find it's best to keep them modest to big will quickly add drag. a grillblock will work wonders, although it can take some experimenting to get it right,

my advice is to keep things simple and black, that way it's easy to change things and black stuff on the bottom of the car will be barely visible, so you don't have to spend a lot of time to make things look perfect. (also a little mud spatter on the mods will blend tem right in with the rest of the car :) )

I haven't seen any real gains with a full bellypan on our 2010 Venza. It is well packaged on the underside also. I believe Toyota has started to address the underside of there cars.

It's a 2011 Sonata (manual).
55mph shows 45mpg
60mph shows 41.5mpg
65mph shows 38mpg
70mph shows 38mpg
75mph shows 38mpg
This is with the built in average computer. Real data says it reads high by 2-3 mpg.

I was wondering about the gains on the belly as it seems a good bit of work if it won't net much. But then again, a 1 mpg increase over time will pay off.

The grill block I am thinking of would reduce the area by half, but from the sides.
Looking at some wide angle racing mirrors, the ones on it are huge.

Before I started looking at the grill block I didn't know where to start (might not still) but the dried rain flow patterns suggests this is a good starting point as the side areas look like they produce the most pressure.

Also looked at how the rain flow at speed was on the windshield and at first I thought I might not need a wiper shroud, but while driving in the rain (with Rain-X) without using the wipers, I noticed the flow from the drivers wiper was stagnant until a few inches above the wiper. The passenger side showed flow much closer to the hood.

The same flow on the rear window mirrored the antene shape.

I also noticed this car not only does not throw up much water, thanks to the 205's, but the overall spray coming from around/under the car is much less than other cars.
Did this by following another 2011 Sonata GLS and watching the effect.

So you drive a 2011 Sonata ... wow. I love the design of that car. When I first saw one I thought it was a Mercedes.
Hyundai really has stepped forward in the design department.
My neighbor has one, and I stop to look at it often.

Stock, your car has an impressive .28 drag coefficient, but with a few tweaks, it can match the .25 Cd that the first generation Insight had.

Stock, your car has a very small grille, I would be cautious about plugging very much of it. The car is designed very well.

The hybrid version has a drag coefficient of .25, yet doesn't look much different from the car you have now. The grille appears to be a massive gaping maw of a hole in the front end of the car, but no doubt it is plugged from behind the slats. ( The bumper is also cleverly disguised within the 'mouth' of the grille, and actually blocks most of the grille area. )
It might be a good idea to see what changes were made to the car to drop the Cd down to .25

http://www.thedetroitbureau.com/2010...sonata-hybrid/

http://www.thedetroitbureau.com/wp-c...id-on-sand.jpg

Hyundai Reveals 2011 Sonata Hybrid, gets 39mpg Highway, can Reach Speeds of up to 62mph in Electric Mode - Carscoop

Quote:

"At the back, there's a reshaped bumper with sharp creases at the corners and revised tail lights. The so-called 'eco-spoke' alloys and beefier rocker panels round off the exterior tweaks that are said to help reduce the drag coefficient from the standard Sonata's 0.28 to 0.25."

The plugged grille :

http://carscoop.blogspot.com/2010/04...brid-gets.html
http://carscoop.blogspot.com/2010/04...brid-gets.html http://http://carscoop.blogspot.com/...brid-gets.html

Notice the creased edges on the tail end : Hyundai Reveals 2011 Sonata Hybrid, gets 39mpg Highway, can Reach Speeds of up to 62mph in Electric Mode - Carscoop

More aero wheels :

http://carscoop.blogspot.com/2010/04...ybrid-gets.jpg

Large portion of the grille is blocked ( look behind the slats as well )

http://4.bp.blogspot.com/_FoXyvaPSnV...a-Hybrid-7.jpg

One of the main things that was mentioned in reducing the Cd was the back end of the car. Notice the stock rear has a more curved bumper at the corners :

http://www.blogcdn.com/www.autoblog....a2011fdopt.jpg

Versus the hybrids sharp cut off ( much like that seen on the Prius )

http://www.jbcarpages.com/news/wp-co...hybridrear.jpg

http://www.autopage.us/images/Hyunda...Hybrid%204.jpg

On closer inspection ..... look at all that crap hanging down under the chassis in that last image !!

Oddly enough, the 2001 Lexus 430 also had a .25 Cd despite having rounded back end :
http://files.conceptcarz.com/img/Lex...burg_03_03.jpg

And a .... blunt grille : ( I hear ya laughing back there Frank Lee ) :

http://photo.netcarshow.com/Lexus-LS...1_photo_05.jpg

Then why on earth aren't they adding these tricks to their entire line ???

I love the new Sonata design too
would love to have one but cant rationalize the price vs the mpg


I wish the hybrid front was more bulletlike instead of that big fake mouth they put

http://www.eylence.az/blogs/media/Hy...ta-2010-01.jpg