it's that rare instance here in so cali where it rains a measurable amount. woke up this morning and the GS, which is parked outside, was all wet from the night's rain. i didn't have time to squeegee the windows off, so i just started driving. Lo and behold, after a few minutes, I noticed that the rear window was completely free of rain...even if i was driving through rain and the front wipers were going every second!! i thought, "ahhh, amazing" and smiled at this little aerodynamic technology that went into the GS. My ES rear windows would always have annoying water spots just like if you left the front windshield "unwiped" through the rain, it was hard to see after a while....but not the GS. except for a few drops in a vertical manner down the center of the glass, it was perfect!!!! yay!

 

well, the windshield and front side windows have a coating to help, but don't know why all the water came off the rear. but its nice.

you also have a GS now?

 

haha, no the GS is my dad's. it will never be mine. (un-knock on wood). seemed to me like the rain never really even stayed on the back window, just trickled down somewhere like the sides. if it rains some more tomorrow i'll deduce it further.

 

Man I wish my mom had leased a GS instead of the E-class so I could have the "GS experience." Hopefully I can persuade her to lease a GS for her next car (even though she doesn't like the look ).

 

The wind from the roof channels the rain down the glass. The rear window is also less steep than that of the ES, which also helps.

 

tidbit - Did you guys know the LS windows are designed to roll off water?


I suppose this same thought went into most of the other Lexus cars. It's nice to be able to look out my side windows while driving and see other cars side windows spotted with rain.

 

does the LS have something special? or is it just aero doing the work?

 

OK, this effect happens at speeds over 45mph, but is most noticeable and best effective past 50 or 55mph. at around 65, theres NO water spots on the back window!!!

 

it's also about the design of drag too. as you know lexus (from what i know, LS, GS, and IS) have very low drag coefficiant (under 0.3 on all 3 models). what that means is when car is going, air will flow smoothly around the car to the tail without any turbulance, etc... happening along the car. so from another perspective, that's like saying there is always a fan blowing the surface of the car, including the winshield

 

so it is aerodynamics then. cause the shape of a car is generally the same, like the profile of a wing, making the air fly over the car and windows faster then the car itself. hah! damned suv's and their rear wipers

who doesn't like that GX though? saw one a few days ago...nice

 

Never even thought that this was a 'feature' since my '94 Mazda MX-6 and my wife's 98 Audi A6 do the exact same thing.

 

It's just laminar airflow over the top of the car. As long as the layer of air stays "attached" to the surface, you have smooth flow (that carries water along with it). When the layer detaches at the trunk (or, say, the rear window on the RX/GX/LX), you get turbulent flow, which in turn deposits all sorts of crud on that more vertical surface. Since you are trying to see out the back of those squared off rear ends, you get a wiper on the glass. But since you don't try to look thru your trunk, you just end up with a dirty trunk and rear bumper on the GS.

bravo261 is absolutely right; it IS like a wing (which is also why the car gets "light" if you go fast enough - the aerodynamic lift provided by that airfoil shape unless some work is done in the wind tunnel to cancel out that lifting affect, such as has been done with the G35 Aero package).

Rain repellent glass is a different matter, but also helpful on the side glass where flow tends to be a little more turbulent.

 

Rain repellent glass - is that similar to what RainX claims it does? Obviously RainX isn't a permanent application but is a cheap alternative. I used it on my old Audi and it worked great. I didn't need to use the wipers when I drove on the freeway since the water just sweeped away. I wondering if I can find that old bottle and use it on the sides and front of the GS to get the same effect.

BTW Mooretorque, you're quite an engineer for being a doctor. I hadn't heared laminar air flow (or fluids) since my college days in ME class. Oh, and occasionally in car mags and such. But your explanation of flow is on the mark from what I remember.

Art

 

Arty, RainX does indeed perform similar function, as a glass wax. And I use it on the side and rear windows of my GS, where it works great and doesn't have to be reapplied frequently (I do it about once a year, based on water beading). On my windshield, I have a pre-treatment that comes with PIAA SuperSilicone wipers. It smells suspiciously like RainX when going on!! And works like it, too. (My GS does have rain repellent glass on the front side windows, but I X 'em anyway.)

Thanks for the compliment re engineering. I did stay awake back in all those physics and math classes. Even if they were 25 - 30 years ago.........

 

Mooretorque-

Thanks for your insight. I better go and find that RainX. I hadn't used it in years, but with all the talk about water repellent glass, I better upgrade both my GS and RX glass via the cheapie method.

I guess that is why you're the doc and I'm the engr. I was able to stay partially awake in my classes.