Why does my car makes a winding sound and it gets louder as I am accelarating and and I can hear it winding down slowly when I release pedal
I would check the transmission fluid and or have the trans serviced.
The Infinity exhaust has a "tune" to it that amplifies acceleration and deceleration. This may be what you are hearing. You don't say how long you have had the car so if you have had it had this noise from the beginning or not, or if it is a metallic sound or not.
Search Infiniti M35 Questions
Are you a UK consumer? CarGurus now has a discussion forum in the UK.
Infiniti M35 Experts