I have only noticed this sound coming from my car since the winter has begun. After a cold start up, my car (2000 SVT) makes this very loud Horn like sound (only of course its not my horn) coming from underneath my car. Usually when I engage first or stay in third or something but keep it in the same rpm range for a second. The sound is at first loud but then kind of just fades out or dies out until the next cold start up. Any feed back. Thanks very much all. Also, car was not affected by previous winters.
Brian

2000 Silver Frost SVT Build # 1724 of 2150 Gun Metal Motegei 17in. rims KKM Induction Kenwood KMD-X92 Excelon Mini Disk Player Pioneer Horn Speakers front & back MOMO F-16 Carbon Shift Knob & MOMO Carbon Door Kick Plates -Door Ding Gaurds Melting tire rubber is a sign of a fast car!