Where to start... should I just drive in reverse?
 

So this is what I'm dealing with: (not my car, but the same shape, minus the hood scoop)
http://www.cargurus.com/images/2009/...208329619.jpeg

Short of rebuilding the back end, or seeing if I can get my engine turning backwards, what can be done? Would some sort of spoiler/wing forcing some air down the backend be helpful or just more drag? I have seen very little about any type of spoiler on ecomodder, which makes me think they are bogus for FE. But it seems like it could help in theory, and for the price of an afternoon, and 3 feet of 2X6....

Any suggestions would be much appreciated.

Those are oversized aftermarket wheels and brakes, right? I hope yours have better aero than that.

The idea of a car with better aero backwards than forwards is amusing, but lots of wagons give that impression. Still, you wouldn't want a rear-engined car with four feet of cargo space in front of the dashboard, so that's why it's shape isn't the best aero.

Your hatch has a really nifty shape that you don't see much of anymore. Check out what Piwoslaw and MetroMPG have done with their similar-shaped hatches. I think it would bring excellent aerodynamic results with little impact on usability.

You could definitely build a good kammback on that.

http://i3.photobucket.com/albums/y93...kammback-1.jpg

Add an undertray and an upper grille block, and that should be good.

Stock, you have a Cd of about .31, which isn't too bad. A few tweaks and you could have a really slick car. :)

That's a nice car, don't ugly it up with boattails and fins.

That's not his exact car, just the same model. You can see the STi brakes poking out from behind the wheels. I doubt he'd be on this site if he had that exact car (:

The modded picture is pretty close to what I've got on mine, and it seems to be the 'low hanging fruit'. The grillblock/airdam up front, then the smooth wheels. I've also lobbed the mirrors off because they're truck-sized and account for nearly 1 mpg each at highway speed. Before doing anything I'd suggest getting a scangauge or some other instrumentation and seeing what works and getting your driving style up (: Otherwise I'd suggest the first aero mod be a grillblock. It's easy to know if you screw that up.

You're right on with driving in reverse:
Teardrop aerodynamics... in reverse!

With your hatch sloped like that there is a lot of room for a Kammback. My roof extension + rear wheel skirts reduced fuel consumption by 8% at 100km/h (60mph). Your Kammy could be longer than mine, reducing the turbulent wake even more. Have a look at my modding thread for details.

Brucey is right: It's easiest to start with a grille block.

Thanks for all the suggestions!

AeroModder,
Thanks. I was trying to find my cars stock Cd for some time. I like the pic! I was also considering pre and post wheel flap things to make them moor of a tear drop.

winkosmosis,
I would agree if my car looked this nice. Mine has more dents, sloppy bondo patches, and is painted about 1/3 in primer.

brucey,
The grill block is number one on my list, as it is so simple, I'd like to do a belly plate too, but a nice strong one, for the off roading that seems to happen now and them... Though it's working agest me for aero, I'd really like to lift it 2" or so and put some larger tires on it someday....
Have you found noticeable benefit from the hubcaps? It seems like a more pricey mod, for relatively little surface.
A scan gauge is high on my list, once I get a job.... the big thing holding be back from that, is that i want a fancy one like dash dyno with data logging, and that is way out of my price range right now.

Piwoslaw,
8%, that's really impressive. And it looks really slick too!



So I will start with a grill block. It seems rather hard to mess it up.
The Kammback will take a little more planing, and playing around, which will happen in time...
I've got to figure out some pic hosting site so I can get some real pics of my car...

The hubcaps I got are just tape and spray paint. Quicker payback (: Good for 3.5% from my own A/B testing.

http://ecomodder.com/forum/emgarage-...8ae920d687.jpg

I've also got a skid plate I put up, probably 50$ in materials and sweat equity.

http://sphotos.ak.fbcdn.net/hphotos-..._5278834_n.jpg

I don't know how much it's hurting/helping, but I drive on my family's farm a lot and have ran over a lot of stuff that's hidden in the grass. So the piece of mind helps. (:

where
 

There are a few schools of thought.
You could mimic the Ford Probe-IV concentrating on mostly the fore-body and go for CD 0.157.
You could mimic the Probe-V double-ended approach and go for Cd 0.13.
Or go for the Jaray pumpkin seed and shoot for Cd 0.09.
The 1934 Chrysler Airflow thread will give you an idea about what tail mods can provide,however you accomplished.

0.31 cd is a good start for a vehicle of that shape - ironically that's no different from a good three-box body sedan! The Subaru Legacy had 0.34 or similar?

At least start with grille block... this should be the default first mod, nice and easy!
Remove roof rack... easy also.

0.31 cd is a good start for a vehicle of that shape - ironically that's no different from a good three-box body sedan! The Subaru Legacy had 0.34 or similar?

At least start with grille block... this should be the default first mod, nice and easy!
Remove roof rack... easy also.

okay, so I figured out photo-bucket, but now photoshop isn't working on my computer. So I did this in paint... I still don't have a good pic of my real car, but this nice black one seems to be working.
Okay so just looking at what might be going on with the back end:
http://i779.photobucket.com/albums/y...g?t=1278355899
and a guess of what would be going on with a kammback:
http://i779.photobucket.com/albums/y...g?t=1278355966
and a guess with a good spoiler:
http://i779.photobucket.com/albums/y...g?t=1278356059
Now my diagrams are lacking reality, but from my interpretations (please correct me) it seems like a good spoiler would work better than a Kammback, but there seems to be very little spoiler building going on here at EM, so I feel like I'm missing something.

duh... high pressure spots, I've just been thinking about the low... but how do they compare in terms of drag....

One of the differences between a Kammback and a spoiler is that the latter is sitting up in the air stream. So even if it improves airflow at the rear, it still produces drag and/or increases frontal area.

Have you tried The GIMP?

I have now! quite nice, but my photoshop seems to be working now, and I know how to use it, so I'll stick with P.S. for now.

That would be one big boat tale....
http://i779.photobucket.com/albums/y...g?t=1278434186

I'm still amazed by this, maybe in a few years if I have another car, lots of money and time, and this car needs a new engine I'll try something with this:
http://i779.photobucket.com/albums/y...g?t=1278434388

and just so you all know this is what my car really looks like:
http://i779.photobucket.com/albums/y...g?t=1278439519

tail
 

The only way you're going to get the drag down is to reduce the wake.
If you had a receiver-hitch,you could get the cheapest cargo carrier and build a 40% boat-tail,which along with your Kamm hatch extension might get you 6-8 mpg increase on the highway.
Just extend,and build upon the gentle boat-tailing which Subaru has already started with the body ( top and sides ),like Breer did with the 1934 Chrysler Airflow.
He 'doubled' it's MPG.

If you do get it going in reverse, take lots of video! I personally would be worried about the rear-wheel steering. That could get VERY hairy at highway speeds.

The general shape of today's cars looks like a reversed teardrop, but there are small details that would kill aero when going backwards. One of them is the small notch at the rear of the roof. Its purpose is to separate airflow so doesn't stick to the rear glass, increasing lift. In reverse this notch would cause turbulance all the way down the roof.
Another detail is the subtle Kamming of the rear half. Most cars designed in the last two decades have a roof which slopes slightly down, with max roof camber above the driver's head, not in the rear. Exeption: PT Cruiser.

http://ecomodder.com/forum/attachmen...5&d=1278485227

Augh! My eyes! Why, why would they do that?

Just another reason it's known as the "PT Loser".