I’ve heard the exact same noise!!! On my 2011 rav 4cyl 4wd. No one seems to know how to fix itBy chance, would this be on the 2.4 liter I4, cruising at lower RPMs, on level ground or uphill, a grinding-resonating sound of "WRAWRAWRA?"
I had a mechanic check into mine when it displayed the above behaviour. They first faulted the exhaust (which was forming a legitimate leak). After replacing it, the behaviour still continued. When I was able to reproduce it, he diagnosed worn rubber braces for the exhaust, which were supposedly allowing the exhaust to resonate. When his colleague inspected the exhaust, however, he re-welded some of the previous exhaust work. Once I left, the noise crept up again.
TLDR; does anyone know anything about rubber braces for the exhaust?