Picked up a 2020 CPO in March and had a consistent rattle from back left that sounded like machine gun (brrrpbrrpbrrrp) at every speed. Not continuous but reproducable. Finally took it to dealer for 30K service. Took then a while with several techs driving while others sat in rear seat. They thought it was tailight but finally tracked it to rear crossbar on roof rack. No idea what part caused it - the rack was tight and pulling on it had no slack. Removed the crossbars and it went away. I am not planning to use the cross bars but wondering if anyone has an idea what component caused it. If I do use them I don't want to hear the brrp again.

 

Hmmm, that's odd. I've never used mine.

 

I wouldn't miss mine either along with the sunroof.

 

Mines was the sliding cover for the rear.

 

"...along with the sunroof."

From your keyboard to Lexus's ears. Or somebodies; anybody. Porsche will let you delete it, but I'm in the wrong tax bracket for one of those.

 

I have the same, exact rattle coming from the front one. It ONLY happens when the temperature outside is below freezing. Once I open Sunruf and firmly grab the crossbar rattle stops. Crossbar sits exceptionally firmly. I checked every screw and every component million times.

 

The cross bar act like a wing and has lift at certain speeds vibration is the up down movement Kind of like the noise that paper makes on a comb while blowing on it. The air movement .causes a vibration , I had the EXACT same issue on another car .and never put the crossbars on my new car. Take off the cross bars.

 

I understand the principle of lift at speed. I had the rattle from 5 -75 mph so it probably isn;t lift. I actually heard it once or twice at a stop. It's totally unacceptable on a lexus to have this rattle. Guessing it's a defect since not all have it but there is no way this car should have passed any test drive before shipping

 

Like a stated earlier cross bar attached extremely tight. I would say solid. Lift wouldn’t make any impact while driving at a very low rate of speed like 5-10 mph or when car is not even moving . Obviously something makes it to vibrate but it is not the Bernoulli’s force)
At least in my case)

 

One possibility is that the frame and body of your car are vibrating at a specific resonant frequency that is in tune with the mass of the crossbar, causing it to vibrate as well. This would be a very rare occurrence but not unheard of. If you don't plan on using the crossbars, remove them. They are worth hundreds $$ on Ebay.

 

It would be safe to assume that your car was never road tested before it shipped as most cars are not. Depending on the quality control program of a particular brand, they will occasionally pick one out to test drive. Extensive testing is done on a prototype before that model goes into production. Other testing is done at regular points during the manufacturing process. The miles you see on a new vehicle at the dealership are usually from previous customers who test drove the car or from the dealer itself.
Only vehicles which are not mass produced are each road tested individually before shipping (Bentley, Bugatti etc).