Underbody noise over potholes
 

I have an RX450h, and am surprised by the loud noise it makes over sharp impacts. I originally assumed that a stabilizer sway link was broken or a strut mount clatter, but the dealer has checked those. It doesn't make the noise over rolling bumps, but a loud clang / thunk / clunk noise over rough roads.

I checked the front license plate and looked at hood bumper stops - don't think it's them.

It's going back to the dealer this week but wanted to get some feedback. I took some time looking underneath and was shocked by all of the hard plastic panels. Fairly confident it's one of those panels (if not a suspension component). All were properly attached, but when you hit them with your hand they make a loud noise. I'm very surpised Lexus does not use formed carpet like BMW and Audi to better suppress noise. I'm also surprised they don't have any foam at connections between panels so they don't make noise. Of course - I could be wrong do does anybody else have this noise? If it's only me it must be something else.

I did a search and found this picture from a previous gen RX. Very similar. The pipe foam insulation may fix it - but again I'm surprised I'm the only one with this noise if so.
https://cimg3.ibsrv.net/gimg/www.clu...92531bc23e.jpg

Any thoughts or feedback? Thanks!

My NX been to dealer twice for clunk over sharp road drops.
First time they replaced both struts, then placed "suspension ears" onto suspension and drove the car. They then "tightened all suspension bolts" and called it done. As service CSR explained to me "bolts self loosened".
Clunk, though in lesser form, came back in about a month later. As I ran out of bumper to bumper on the 25th of the last month, I brought it back on the 23rd. They "drove car for 10 miles and found nothing". I have serpentine on my way to HWY with a crack across tarmac, going down - where I can reproduce clunk 10 out of 10 times. I simply don't want to deal with dealership anymore. If something breaks, they have it listed twice that customer expressed concern.
I doubt it's panels in your case. Though maybe. Panels do very distinct plasticy sound, it's easy to differentiate from metal clunk.
Reason I mentioned my NX just to show, how quality is not really there. Self loosening bolts? Seriously?

Thanks for your reply ukrkoz. If it is the plastic panels, I would assume I'm not the only one with these noises. I guess I'll wait and see if others provide feedback.

Do the easy one first. Check to see if you have a loose tool and/or out of place car jack under your carpet in the back of the SUV. Good luck

As a follow up. The dealer replaced a front strut that was knocking and it fixed the noise. Happy to have the knocking noise fixed!