The optionally available COMAND APS control and display system (standard in SLK 55 AMG) not only guides you to your destination, it entertains you as you go. The innovative multimedia system features a hard-disk navigation system plus an integral radio and DVD player and a MUSIC REGISTER with 4 GB of hard disk space for compressed audio files. It also lets you operate the optional Harman Kardon Logic 7® surround sound system with Dolby® Digital 5.1/DTS and 500 watts of output, the DVD changer and the telephone – with the option of voice control. A Bluetooth hands-free system is standard equipment on board and also already comes as standard in conjunction with the Audio 20 CD and Audio 50 APS systems.