Strange clacking noise

When driving my 9-5 Aero (e.g. when parking from a parking space when driving heavily) I noticed a strange metalic crack sound. During the ride there is nothing to hear about it, but from the stand it is noticeable. Otherwise I do not notice any abnormalities when driving/driving, it is now naturally noticeable when driving with an open window…. Do you have this with your 9-5 too or my black devil has a problem( little)…because otherwise everything is dazzling…?