Hello to everyone,
I have recently bought a new Rx 350 (2008). When I start the car the engine seems to grumble for a few minutes.
(Noticeable only to very picky people like me). I have asked my lexus dealer and they said it is caused by the computer adjusting.
Could this be the case? ( a faint knocking sound)
Thank You!
Respect Simon

your car's RPM's do run high in the begining its normal.

yes... would not worry about it.