There are three USB ports in the Mercedes-Benz GLC300, located inside the armrest box and near the rear air conditioning. With a total of 6 USB-C ports and two 12V sockets, you and your passengers can easily power mobile devices. Does the Mercedes Benz GLC offer adaptive cruise control? Yes, the Mercedes Benz GLC offers adaptive cruise control, which helps maintain a safe distance from other vehicles on the. The USB ports in your GLC allow for effortless integration of your devices, making it easier to listen to music, charge your phone, or even navigate with your favorite apps without fumbling with wires. I'm trying to figure out what the 2 USB ports do.