I have noticed that on about 1/3 of cars and SUV's there is a small
black angular piece (larger than a jelly bean, but smaller than a golf
ball) usually centered above the rear window.  On some cars it is
shaped like a fish fin, on others more like a half moon.

What is this and what does it do?

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Clarification of Question by research_help-ga on 20 Apr 2005 12:59 PDT

I appreciate all the comments so far, but I don't think we have it yet.  

This little "thing" is found on my car and others that do not have an
external antenna, GPS, satellite receiver, or rear window washer.  So,
I do not think it is any of these.  However, I could be wrong, but I
don't know why a car manufacturer would install this piece if the car
did not even offer the functionality as an option.

Omnivorous - the picture you found does seem to show the "thing" we
are talking about.

---

Clarification of Question by research_help-ga on 21 Apr 2005 09:49 PDT

Pinkfreud - you were the first to get it right. It is a rear window
washer sprayer nozzle.

I was sitting in traffic today, and lo and behold, the guy in front of
me started cleaning off his back window using the rear window sprayer.
 I was perplexed why my car would have the black "thing" if I didn't
have a rear window washer.  It turns out that I do have a rear window
washer but didn't know about it.  It's a semi-undocumented feature
that I activated twisting the wiper arm in a way I had never tried.

So, Pinkfreud go ahead and give me the official answer.

I'm glad the mystery is solved! This was an enjoyable thread. 

And the answer is...

Rear window sprayer gizmo!

It's interesting that this led to your discovery that you have a rear
window washer. You'd think that a neat feature such as a rear window
washer would be something that the manufacturer would want to make
obvious to the owner. Sometimes I am baffled by the way that
automobile manufacturers hide things that should be obvious. A few
years ago I bought a used car, and the first time it needed gasoline,
I spent over an hour trying to figure out how to unlock the gas cap.

Best regards,
pinkfreud

You learn something new every day

A built in cell phone antenna; GPS antenna, maybe something you can
rub for good luck in traffic if you don't have St. Christoferus statue
on your dashboard  - or a  blue and white glass "eye" hanging from the
rear view mirror to ward of evil?
Odds are, GPS, I think.

Some vehicles have rear-window washers. I wonder if this doohickey may
be the sprayer.

RH --

Though she used highly technical jargon to explain it, I think that
Pink has it.  An image of such "jellybean like" device on a PT
Cruiser:
http://www.etchedglassart.com/images/Figurative%20Work/Jill's%20PT%20Cruiser%20rear%20window.jpg

Google Images search strategy -- and make sure "car" or "SUV" or
"minivan" is in there or you'll just get movie posters:
car rear window

Best regards,

Omnivorous-GA

i am not certain, but i would be willing to guess that it is the
antenna for the radio and the satallite (sp?) radio.

-dave

Does this look familiar?

http://www.onlinecarstereo.com/CarAudio/assets/ProductImages/SR2.jpg

Here's a close-up of the spray nozzle of a rear-window washer:

http://gallery.genvibe.com/albums/04miniMich/DSC01454.sized.jpg

I appreciate all the comments so far, but I don't think we have it yet.  

This little "thing" is found on my car and others that do not have an
external antenna, GPS, satellite receiver, or rear window washer.  So,
I do not think it is any of these.  However, I could be wrong, but I
don't know why a car manufacturer would install this piece if the car
did not even offer the functionality as an option.

Omnivorous - the picture you found does seem to show the "thing" we
are talking about.

If its on the glass, like on Omni's link, and yours it too, then at
least you can tell if it has a hose (spray) or electrical connection.
If yours is on the metal above the rear window, are you sure that a
GPS navigation system is not offered by the maker, or that the maker
doesn't provide the antenna connection for installation by someone
else?  Ditto for a cell phone connection.
OR  could it be the antenna for an alarm system?  I think my Volvo has
a little "doohickey" like that, although I don't have the alarm.

I just took a walk to my neighborhood ATM machine.  On my way I
conducted an unscientific survey.  I took a closer look at each of the
several parked cars I passed along the way that sported a protrusion
like the one you described. Every one was positioned right above the
rear window and had a hole in the bottom of it.  And they all had a
"windshield wiper" attached to the window.

RH --

A neighbor has a PT Cruiser very similar to the picture in the link
that I'd posted.  It is indeed the spray unit for the rear window
washer.

Best regards,

Omnivorous-GA

Hello research_help-ga,

Take a look at these. I think you're talking about the windshield
wiper spray nozzle. In my search I found lots of rear windshields
without this little "thingie", even cars that had rear windshield
wipers. However, I didn't find any cars with just the "thingie" and no
rear winshield wiper. As I searched, I discovered that LED windshield
sprayers nozzles for the front sprayers are quite popular so I've
included an example for you.

I think Omnivorous and Pinkfreud had it right on identifying the "thingie".

http://www.fc3s.org/car_of_the_month/images_november_2002/rear.jpg
Top middle -- rear windshield wipers

http://photos3.flickr.com/3615707_4cce36cd48_m.jpg
Top middle -- rear windshield wipers

http://www.allcarpictures.com/acura/mdx-picture-018.htm
Top middle -- rear windshield wipers

http://www.rdmelton.autoeducation.com/cars/talon/before/rear-1.jpg
Top middle -- rear windshield wipers

http://www.prolightstar.com/accessories/jkl_led_nozzles.html
LED Windshield Sprayer Nozzles

Pinkfreud - you were the first to get it right. It is a rear window
washer sprayer nozzle.

I was sitting in traffic today, and lo and behold, the guy in front of
me started cleaning off his back window using the rear window sprayer.
 I was perplexed why my car would have the black "thing" if I didn't
have a rear window washer.  It turns out that I do have a rear window
washer but didn't know about it.  It's a semi-undocumented feature
that I activated twisting the wiper arm in a way I had never tried.

So, Pinkfreud go ahead and give me the official answer.

Thanks for the five stars and the tip!

~Pink

research_help,
and I bet you live in the Southwest.

Take a look at the picture of the Hyundai Santa Fe, the window washer
sprayer is on top of the windshield. The doohickey is offset to the
right on the bottom of the windshield wiper. That doohickey is a
device for you to recess the wiper blade when you open the windshield
instead of opening the entire hatch.