aero piece / flap on rear window of newer suv's and cars.
 

im seeing more of these style flaps on the back of suv's. has anyone tried to immitate this or copy something similar with some noticeable results? see images

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this was on a mini clubman. bt also visible on all newer ford suv's. audi's and some bmw's. the range rover evoque also has some. what difference can i expect modding my 2005 ford fiesta hatch like this?

Ah - good catch !
That's a perfect example of a 'trip strip' - thanks for posting .
I have seen similar on the tail lights of a Ford Fiesta / Focus, where there is a small ramp to detach the air before it goes turbulent.

Is that the legit term? "trip strip"?

It's a popular term around here. Basically just a sharp edge that enables clean separation instead of the air trying to wrap around the radius of the edge and create turbulence. MetroMPG made some nice ones for the back bumper of his Civic. I guess in a way it's like a miniature box cavity just like the little spoilers on most new cars are mini kamm backs. It's the designers adding little bits that still look good while performing a specific function.

I've also heard a 10 pack of LSD called the same thing. lol

These are actually a spoiler for wipers but could see them made to fit on a fender.

Deltalip Aria Bonnet Wiper Spoiler s Size 100cm 39 4in Mitsubishi Mirage Colt | eBay

I was originally looking at these to get cleaner flow up to the roofline.

Lmao, nice!

Those looked great until i saw that $45 price ! AAAACK !

Oh and yes i laughed as well at the 'trip strip' comment !

pics
 

these are what i plan on using. im into modifying my car put i dont want it looking silly. these are paper binding clips
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Neat idea Eddie! After seeing Metro's bumper ones I've been thinking of doing the same to my curved bumper but couldn't really think of a easy way to do it, I'll have to give the folder clips consideration.