I plasti dip the entire back side of the license plate and it reduced the rattle.

 

https://www.walmart.com/ip/Camco-250...-30-L/46529213

 

get some dynamat , cut them into strips and apply it along the perimeter of your license plate.

 

I've had those felt pads on mine for a year and a half including a Michigan winter with no problems. If they rot out replace them they're dirt cheap

 

interesting,

I noticed it on my RCF and it was annoying, while I noticed it closing the trunk, it also rattles when your radio is turned up (sub thump) and going over bumps. Over time I noticed the vibration was damaging the paint, I had my detailer buff out as much as he could and then I installed these onto the back of the plate:




I noticed that Toyota seemed to be aware of the issue because my wife's new 2017 Camry has 4 felt bumper pads at the corners of where the plate goes, so her plate doesn't' touch the car nor rattle.

 

^ I just did this to my 16 200t. I superglue two of these on the lower corners of the license plate. No rattle, and not risk of anything on the plate scraping against the car.

I did the same on my 06 TSX and they lasted 10 year.

 

yeah I prefer to have it on the plate, putting Velcro or anything with adhesive onto the car risks paint damage. Don't care if I damage the state issued plates.

 

Yep. Velco strips like this: http://amzn.to/2e0mspn

Just cut to size. Been doing it for years. No rattle. Put a layer on the plate frame (the soft felt like side only) no need to use the "hook" hard side. Thin strips.

 

I just buy some adhesive back door weather striping foam homedepot, stick a small square on each bottom corner, and all snug with no rattles anymore.
http://www.homedepot.com/p/Frost-Kin...734H/100047977