my mercedes benz c class 230 2007 is making a whistling sound from the engine

What is your question?

it seems to happen when i slow down at first i thought it was an ambulance then i relized it was my car making that sound

What makes this problem better or worse?

im not sure i had been driving the car for about an hour

How long has your 2007 Mercedes-Benz C230 had this problem?

just started