Hill Descent Control (HDC) holds the vehicle steadily at a pre-determined speed, helping with the job of brake control so that the driver can concentrate completely on steering. This makes the potentially difficult task of driving down a steep hill or over rough ground easy. Still have questions? Call our BMW Genius Hotline at 1.844.4GENIUS (443-6487) Available Monday through Thursday 9:00am-9:00pm (EST), Friday 9:00am-6:00pm (EST), and Saturday 10:00am-7:00pm (EST) For portable assistance available anytime, anywhere download the BMW Genius App at bmwgeniusapp.com If you would prefer to send us an email, please contact: bmwgenius@bmwusa.com You can also refer to your owner's manual or visit: bmwusa.com/owners-manuals.html Connect with BMW USA: Website: bmwusa.com Facebook: facebook.com/BMWUSA Twitter: twitter.com/BMWUSA Instagram: instagram.com/BMWUSA Tumblr: BMWUSA.tumblr.com