Story of the weird Prius roof ?

I think I read it on a Toyota web site about a year or so ago.
Remember you need to get in and out of a car, be able to see out of it without distortion, air needs to access radiators and there needs to be wheels to keep it off the ground and it has to be something you wouldn't be ashamed to be seen in.

 

Here's an older thread on the subject.

http://priuschat.com/forums/prius-technical-discussion/23428-prius-roof-design.html

 

That sounds plausible, but are the bumps on the inside, too?

 

I don't know that they are but the head lining is very flat right to the side rails where other cars the head lining is curved down near the rails.

I just checked with a straight-edge and the centre of the roof top is actually higher than the sides out to the seams. The side rails are higher to limit the flow of water over the side windows off the roof, a common way to eliminate rain gutters on the edge of the roof.
The head-lining is flat across it's width until it takes a sharp turn down at the side rails according to my straight-edge. As I said earlier most cars have a curved head-lining. I'm guessing the fore aft curve of the roof allows the head-lining to support itself in an arch.

 

as i have posted before, the spoiler does not really ruin the view out of the rear, because the rear view underneath the spoiler is typically "bonus coverage" and in any other car
that part would be blocked off by your trunk, rear seats, etc....

 

The vertical headlight arrangement has always rminded me of the "over-under" headlights (as they were called) of the '65 (& following yrs) Pontiacs, of which I was enamored in my youth.

 

Pat,

I'm usually behind what you say 100%, but on this matter I beg to differ.

The creases where the humps meet the center flat section are right over the
driver's/pax' heads. At the roof's edge, the hump is curving down, not
parallel to the ground. I wouldn't expect the head liner to follow the roof
bumps. Between the roof and headliner, I suspect that there is a high
strength steel member connecting the two sides of the car at the "B" pillar.
(Or is it the "C" pillar, the one where the front/rear doors nearly meet?)
And it would be counter productive to have creases or humps in that
member.

I think the answer is somewhere between aero' and art. After reading of
your exploits with the straight edge, I went and looked really closely at the
bumps. They are formed by two arcs. One from front to back. The other
from side to side in a roughly horizontal plane. The high point of the fore-aft
arc and the centermost reach of the horizontal arc are at the same point, as
near as I can tell.

Coincidence? I don't know. Aero or art? I don't know. And I don't think we
mere mortal consumers will ever know until we get a degree in
aerodynamics, get free, unlimited access to a wind tunnel, and look very
closely at a Prius ... while the world and the Prius' design marches on ...

FWIW, my much devalued $0.02 US.

Edit: Fundamentally, I see discussions like this one as being about as
important as debating how many angels can fit on the head of a pin.
No matter the outcome, our lives won't be significantly changed, and
the eternal fate of our immortal souls is not in the balance. So, I say,
pull up a chair, open a cold beer/ale/stout, and let's discuss...
friendly-like of course.

Pass me another beer will ya mate?

 

In saying the shape of the roof is how it is to reduce frontal area while maximising headroom, I was only saying something I had read elsewhere. It may well not be correct.

In looking for the document I originally saw it in I have stumbled on a document which is the story of Prius developement, if anyone has several hours to spare it is facinating reading.
http://www.chicagopriusgroup.com/resources/Prius_that_shook_world.pdf
Downloads

 

A good read, I was up till 4AM reading it. Finished it today.
I don't think it's quite that big, it was in original form which is annoying as it has page numbers in the text. It's 104 pages at A4 size and pretty big print.