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

[womprat]

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.

[Dr. Jerryrigger]

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:

and a guess of what would be going on with a kammback:

and a guess with a good spoiler:

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.

[Dr. Jerryrigger]

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

[Piwoslaw]

Originally Posted by Dr. Jerryrigger

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.

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.

Originally Posted by Dr. Jerryrigger

but now photoshop isn't working on my computer.

Have you tried The GIMP?

[Dr. Jerryrigger]

Originally Posted by Piwoslaw

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....


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:

[Dr. Jerryrigger]

and just so you all know this is what my car really looks like:

[aerohead]

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.

[iplaysdrums]

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.

[Piwoslaw]

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.

[RobertSmalls]

Originally Posted by Piwoslaw

Exeption: PT Cruiser.

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