2007 RX 350 Growling Sound

[KJ Perkins]

Started car this morning and it made loud growling sound at startup and accelleration.  Sound quited when car was parked, but made same sound when I pressed pedal while parked.

[sha4000]

Your too vague, we need more clues. Is this the first time that this has happened?

[RX400h]

Have you opened the hood and watched/listened to the engine while someone else revved or brake-revved the engine?  See if you can isolate the sound location.