What Car? Q&A - Why does my Golf boom?

Q: I purchased from new VW Golf Mk4 five-door in January 2004. When I am driving over 30mph, with the rear windows down, there is a booming sound covering the whole interior of the car. This is remedied by raising the windows fully. I mentioned it to the service manager of my local VW dealership, only to be told that it was a feature of this particular model. What advice can you give me?
Robert Allen

A: The symptoms you mention are not uncommon, and occur on many cars. The booming noise is caused by having the windows open, allowing air to enter the cabin of the car. As the air is unable to escape, the pressure inside the car rises slightly until it is high enough to force its way out of the open windows. The buffering you hear is the sound of the air building up and then escaping. The only real solution is to close the windows.