I have a 2002 C320. Everytime when my car is in Drive and I take my foot off the brake and let the car coast by itself I hear a really loud screeching noise that is very annoying and embarrassing. When I hit my brakes or speed up the noise goes away.
Can anybody please help?? I have no clue.
I also recently had my car serviced also with the regular oil change, power steering fluid, and brake fluid.

Thank you, greatly appreciated

 

just a simple thing maybe a heatshield rubbing on exhaust. see it alot.

 

You might need new brake pads. Some pads have what is called a wear indicator. Its a little piece of metal that touches the rotor when the brake pads wear to a certain thickness. Now, before someone jumps in and reminds me that we have electron sensors, (heheh), It may be a pad or it may be the dust shield touching the rotor, but that would squeal almost all the time.
The clue here is that it goes away when you put the brakes on.

 

Intermittent screenings can be commonly due to slipping drivebelts and sometimes pouring water over it stops the noise which then proves the point. As it's auto tensioned, changing it it would be the answer.