So I am looking to become part of the IS crew. I've been looking at a few and I have seen 2 with this piece hanging off the bottom. What is it exactly? It is the body colored piece on the underside passenger side.

 

Welcome to the forum!

If you're referring to the plastic piece just under the bumper in front the passenger front wheel (in your pic above)...it's actually not supposed to be body color. That's red flag number one that the bumper on that car has been painted.
The part is supposed to be a natural flat black plastic finish.

The part is actually a deflector that will deflect the air and some road debris around the front tires.
Some don't find it aesthetically pleasing, so they remove them. It's not the end of the world if they are missing.

There was an older thread discussing this part: https://www.clublexus.com/forums/is-...e-flaps-2.html

 

Oh, thank you so much Sasnuke.