I feel like this has been brought up before but haven’t had much luck finding the thread on it.

Walked out to my car this afternoon to find an odd buzzing noise coming from under rear of car. This was about 8 hours after I last drove it and went away after a quick startup.

 

It's normal. My 2018 IS 350 did this.

 

Yup this is normal it happens.

 

Can confirm this is the same noise I've heard in mine as well. Your car is not broken.

 

That definitely adds up but very much catches one off guard as it happens so long after the car was last driven and seemed to go on for a while !!! Had plenty of time to look inside & under the car for the noise’s source, then go back into house to grab phone and record a video.

Regardless thanks for all the input. Now to find the source of that irritating buzzing noise from a-pillar under moderate acceleration !!!!

 

The first time I heard the noise was when I had my 2018 IS 350 and I was walking near the laundry room which is right at the access to the garage and could hear there was a buzzing coming from the garage. It was late at night and I opened the door and heard it quite loudly. Needless to say I looked it up and found the answer quickly. I have yet to hear it on the IS 500 yet but I assume it's doing that secretly while I sleep.