I have a strange rattling sound coming from the driver side area outside the car. BUT ... I only hear the rattling sound when I get over 50 mph. I tried to narrow it down but still no luck. Here is what I investigated so far
1) Thought it was the driver side front wheel or underside molding ... Pulled wheel and looked at the plastic molding ... Some loose so I made sure it was tightened ... Still hear noise
2) Checked the luggage rack ... Removed railings and still hear noise
3) Removed the driver side door panel to check for anything loose ... Did not find anything out of order ...
4) Tightened driver side mirror ... still hear sound

If anyone has other ideas or had the same problem then please let me know. Thanks!

 

You'll get more informed responses if you put this post in the 2nd generation forum. This one is for 2010 and newer.

 

Most likely it's a loose gas tank shield. Check out this forum posting:

https://www.clublexus.com/forums/rx-...50-rattle.html

 

Had the same issue 2008 RX350 and it was the plastic cover drivers under side (gas tank cover)
I trimmed the piece that became loose and that did the job. Now I have to mount back the cross bars I removed from the roof thinking it was that.

 

Check the heat shields above the exhaust pipes, toward the front. The shields corrode around the mounting bolts and then hang down on the pipes causing a rattle. Common issue.

I just removed the bolts and added larger "fender" washers. been quite ever since.

 

Thanks for the responses ... I will check it out!