Remove rear wiper.

I don't think so. The difference would be so small that anyone would not be able to prove it makes a difference.

 

You would gain more mpg by "removing" the passenger or significant other, if you have one, from your commutes.

 

or.........wearin a bathing suit.....like where you're at

 

I think once the air passes the high point just above the windshield, it's moot. At that point, the air can only be factored as down force not resistance.

 

Visibility?
Yes.
(Aerodynamics) Mileage?
No.

I think in 40,000 miles I've switched my rear wiper on less than five times. Notice that I said that I switched it on....NOT that I used it as a wiper. The only reason it's still on 'my' car is that my car isn't MY car...it's a company ride.
Otherwise I would have done a rearwiperectomy a looooong time ago.

 

You would get better results by Removing the Spare Tire.
WAIT, Toyota already did that for you !!!

 

What is the purpose of rear wiper anyway? I haven't had the car long but I've never had to use it. It was on my Integra hatchback as well that went unused.

 

I use it all the time when it rains or snow.

 

to clear the rear window? lol
i also assume it's required by law because every hatchback and station wagon i've ever seen has had it. also, the rear wiper on the Prius c is hilariously small. it's barely the size of my (rather small) hand.

 

yeah, it's for lazy people like us that don't want to remove the snow by hand

 

The rear wiper has had its uses here in Virginia, where there has been a lot of rain lately.
And if you really want to improve the aerodynamics of the car, you can remove the side mirrors. But who would want to do that??

 

The Porsche 911 my coworker drives doesn't have. But if its use was to clear the window, why aren't they on non hatchbacks? What makes seeing out the back of a hatchback more important than a sedan or coupe? Makes no sense.

 

i've spent the last 90 minutes attempting to find the answer to this question without much success.

supposedly, the reason that wipers are more necessary on station wagons/SUVs/minivans is that due to the steep(er) drop off of the window, there is a low-pressure zone that is created around the rear window, and so rainwater is not "pushed down" the window and needs to be cleared manually. in a sedan, the air flow running over the back pushes rainwater off. in my personal experience, however, i'd argue the opposite is the case, because the steeper window allows water to be brought down by gravity.
another point is apparently that because non-sedans lack a trunk, much more roadway dirt, etc, gets picked up and thrown on the rear window, whereas on a sedan, the trunk provides a buffer so that most dirt ends up on the bumper/license plate area. since non-sedan windows get dirty quicker, a wiper is added to the back for convenience.
i could not, however, find any regulations mandating this. and i tried! nothing in the US and nothing in Europe, and I don't know Japanese at all, so can't really search there.

 

A member of EcoModder is performing tuft tests on his new 2012 Prius. From the videos I have watched, the rear wiper doesn't impact aero much.

Second part of the video is without vortex generators.

 

In the northeast we have lots of salt and sand on the road after snow storms. When it gets wet those solids get airborne/atomized by the air and tire movement. The vortex draft of the flat-backed car sucks up that atomized salty mud and essentially spraypaints the rear window dark. Without the rear wiper the rearview mirror is useless. (It is for the same reason that we New Englanders don't pay any attention to crosswalks, which are invisible under the salt/sand if they haven't been abraised off the tar altogether. )

 

Alright, here's my theory. Vertical windows like on wagons and vans require wipers due to aforementioned vortex. Notchback sedans and coupe don't have this problem because they have a trunk. Intelligent lawmakers decide to make laws that wipers are required on hinged rear doors. So even though the Prius and Integra hatch is slanted, they have to have rear wipers. I just completely made that up right now.

 

i would agree with you, but like i said, i couldn't find any regulations on this in either US or EU.
some forum post somewhere mentioned a "quirk" in Japanese regulations in the 90s. why this would still have an impact today i'm not sure, nor can i find the relevant laws since i do not know Japanese at all…

 

I think the lower rear window on the Prius requires a wiper more than the upper. It is vertical and attracts dust on dry days and muddy mess on rainy days. I have to manually wipe it off every few days to maintain the rearward visibility on rainy days. Ironically, the upper window where an wiper is equipped, stays clean on its own without the use of the wiper.

The backup camera lens gets nasty in rainy weather too.

SAMSUNG-SGH-I747 ? 2

 

While I doubt that we can notice the difference, I'm sure the car makers can measure it in the wind tunnel tests. And since they had to add up many 0.05 mpg increments to be able to round up to that magic 50 label, rather than having to round down to 49, they did pay attention to this.

My original hatchback had a horizontal rear wiper, where the slipstream hit it broadside. All the household cars since have had vertical rear wipers, so the the slipstream hits them end on, a much smaller drag cross-section.

I used all mine. DW still has her Integra hatchback, and is annoyed that the rear wiper has failed. She wants me to fix it, I want to replace it with something that has airbags and ABS .