Interesting. I also had no idea. Obviously for aero.

 

Seems useless to me. Adds a little drag and doesn't help the look. I'm shocked more cars aren't shaped like teardrops. All the car magazines in the 80s and 90s had pictures of future concept cars looking like that. But instead we get ugly for EVs, like the i3, front end of the tesla model X, front end of the volt, the fiisker, the leaf. Why can't they make an electric car drop dead gorgeous? Oh yeah, they did, that's the ELR.

 

I'm shocked more cars aren't shaped like teardrops. All the car magazines in the 80s and 90s had pictures of future concept cars looking like that.

Contrary to popular belief, teardrop shapes are not the most aerodynamic design. Otherwise, airplanes and rockets would be that shape.

 

Steverino pointed it out months ago as a NACA duct. It's probably somewhat effective at reducing drag.

 

No, it's not an NACA duct, since there is no inlet.

It could be for reinforcement/strength.

 

"The sculpted lines are inspired by sands blowing through the wind."

 

I agree with Mr. Dave its probably a form of vortex generator.

 

In addition to air flow, the ridges also strengthen the roof more than a smooth roof. Same with the hood.

 

another thing that came to me is that if the roof height isn't needed in the center for egonomics for our heads. Then lowering the roof height in the center effectively reduces the frontal cross section pushing less car through the wind.

 

Then why not lower the entire roofline and get an even lower cross section? Though I'd like to see a voltec with a raised roofline
In the form of a wagon. My 5'11" daughter hates the rear seat of the g1 as her head has to be positioned behind the head liner just underneath the glass.

 

anybody drive thru a rain storm yet.how dirty is the back of the car getting?

 

The last 1/2 mile of road to our house is unpaved, and rear-end dust is a real problem, especially under the deck lid. The California Duster is somewhat helpful, but if our V was a dark color, it would be impossible to keep it looking spiffy!

BTW, while a teardrop shape is ideal from a fluid dynamics perspective, the work of Dr. Wunibald Kamm is the basis for most modern aerodynamic automobile designs. From Wikipedia:

While the realities of fluid dynamics dictate that a teardrop shape is the ideal aerodynamic form, Kamm found that by cutting off / flattening the streamlined end of the tear at an intermediate point, and bringing that edge down towards the ground, he could gain most of the benefit of the teardrop shape without incurring such a large material, structural, and size problem. The airflow, once given the suggestion of the beginning of a turbulence-eliminating streamlined teardrop tail, tended to flow in an approximation of that manner regardless of the fact that the entire tail was not there. This is called the Kamm effect.

 

Thanks for the reference. That still doesn't explain why there aren't any cars that look like the fron of a teardrop with the tail chopped off.

A modern version of this could look quite striking

http://www.spiritoftomorrow.com/uploads/1/6/2/2/1622945/9765292.jpg?557x374

 

Yes I believe this a form of the pagoda roof design. The Scion FR-S has something similar.

It provides some benefits to airflow, while adding strength as Raymond mentions.

 

That's for the reference. That still doesn't explain why there aren't any cars that look like the front of a teardrop with the tail chopped off.

A modern version of this could look quite striking

This one came pretty close, and it is indeed, "quite striking"

 

This one came pretty close, and it is indeed, "quite striking"

View attachment 90250

Or this

 

Don't forget Buckmeister "Bucky Balls" Fuller's Dymaxion

 

I'm guessing this means no aftermarket sunroof.

 

Something that I was unaware of since most of the photos don't really show this... the roof of the 2016 Volt has this indentation with curved ridges. I took this picture last weekend at the O.C. International Auto Show, where Chevy had two 2016 Volts. A black one and a white one.

Already brought up. http://gm-volt.com/forum/showthread.php?185538-Aftermarket-sunroof

 

Prius (C and V models) have this roof design. I'm not sure if the (non-solar paneled) traditional Prius model has it or not.

 

All Prius models begining with the 2004 MY and up have a similar roof design. (Except 2010+ Solar-sunroof models)

I remember reading a technical paper that stated that it helped with aero, and reduced "spill-over" of air flowing over the roof to the sides of the car.

The Dodge Viper also has a similar design, but I belive that is more for style and headroom reasons.

 

A car with a tear drop shape. Too bad the Aptera did not make it to production.
https://www.google.com/search?q=apt...5&source=lnms&tbm=isch&sa=X&sqi=2&ved=0CAcQ_AUoAmoVChMI96exov3byAIVgzuICh38DQq0

 

Rain water dispersal system...

 

That definitely is a NACA design for improved aerodynamic flow, They did extensive wind tunnel testing on it. A teardrop design can be aerodynamic but there would be a lot of useless space toward the rear with no collision protection. Optimal aerodynamic flow occurs at approximately 3.5 to one on length vs width.

 

Agree with many of you. Definitely adds structural integrity without adding a lot of weight. But the shape indicates generation of vortices that rotate from the roof to the sides. Must help the flow behind the car which is where the majority of drag is generated. The shape does not really act like a NACA duct per say since it's external flow instead of internal flow, but I can see where calling it a NACA duct would add good PR. I also wonder if it induces transition as well, but I'd have to know if the flow was laminar on the roof. Probably isn't but I'm not terribly experienced with low Reynolds numbers flows.
The whole point of the tear drop in back (cusped trailing edge) is to remove flow separation which is the major source of drag on a car. Problem is that it lengthens the car without adding useful payload space..if a car is too long, it won't fit in a parking spot for instance. Cars all about most payload space in the smallest package.
Airplanes are shaped like teardrops...airfoils in wings have sharp trailing edges for a reason.
Rockets don't need a sharp trailing edge because the plume of the engines keep the flow on the rocket itself attached.