Hi people. I'm a new member and a first time Lexus owner but I have owned several cars including three Camrys. My daughter also owns a Rav4, so I have worked on Toyota products before. I've been doing my own maintenance since 1965. I was also a licensed mechanic for several years but I have not done any training on electronics. So I am knowledgeable and sort of know what I'm doing, but there's always an opportunity to learn from others. There are so many helpful members on these forums (fora?) and I've been on the Acura and BMW sites as well. So I will now get to the point!
My new used car is a '17 IS350AWD with 38 K km. It drives well but I'm going to replace all the brake rotors and pads. The rotors are pretty rusty. The wheels look great and the tires look very good. Stock Turanzas. But interestingly, if I drive at 100 clicks (62mph) and roll down the back windows, I feel and hear this extreme pulsing/vibration coming from the back. It sounds to me like tires with internal delamination, or a frozen CV joint on an axle. Have any of you experienced this? I never noticed it before I purchased because I never thought to lower the rear windows on a test drive! I'm 90% sure it's not the brakes, Today I'm taking the rear wheels to have the balance checked. I'll let you know how this story unfolds. Jim

 

Well, holy cow! I took my tires/wheels over to my local tire shop and left them to be balanced. They are busier than a pub with free beer.
But.....one of the mechanics tells me that this "pulsing" when a back window is open is standard now and is not a mechanical problem. He says all new cars do it to some degree. He says it has to do with the aerodynamic designs which are now prevalent on most brands. So I guess that's good news. This is believable to me because the "problem" is not there at slow speeds, only at highway speeds. I'd love to hear any comments from others on this. I guess I learned something today.

 

Yes it’s normal on most any modern car with a decent seal/ wind proofing. often referred to as helicopter effect. Roll down another window it’ll stop

here is a more scientific explanation text from an old Reddit post

 

Thank you very much Dave, for the info and the response.
I used to be a physics teacher and I know about Bernoulli and Helmholtz, and I sort of thought of that, but I was shocked that a car would be made nowadays so that you can't drive it with a window down! I confirmed the effect is also present on our '14 Ford Edge.
I guess it's mostly good news though, if there's nothing really wrong with my car!
Again, thanks for the reply, I really appreciate it.
Another example of resonance is dramatically illustrated by the Tacoma Narrows Bridge Collapse.
I think it's on Youtube and very much worth a look.

 

I was about to post this but hesitated since you mentioned the rear wheels. It's unthinkable yet somehow true that many modern cars suffer from this issue. The Supra is particularly bad for some reason.

 

Thank you arentz07! As I said.....Holy Cow! Yes, it seems to me to be outrageous, but I'm not a car designer. The resonance effect is so intense. I'm glad to know there is nothing mechanically faulty. I envisioned many hassles with the dealer trying to get them to fix this! As Dave indicated above, "Helicopter Effect" is pretty descriptive of this phenomenon.
Jim

 

Extreme pulsing low freq vibration while driving with real windows down? ehm... that would be a case of extreme buffeting due to aerodynamic. It is dictated by the shape of the body and other things...

 

Yeah, unlike alfa giulia, Our ISs were clearly NOT designed in a Ferrari wind tunnel...

 

Thanks for posting. Several people have told me this is normal with new cars. The mechanics at my local shop also assure me it's "normal".
I'm still surprised that the car companies allow this, but I suppose it's not an easy fix at all. So I'm happy to know there's not a mechanical problem with my car.