You need to get the "SYSCFG.TXT" file onto your Micro SD card first - See Page 9 of the instructions (Hold down Mode 'M' button & then also Power Button together until the top RED LED flashes 3 times and camera turns off, then release these two buttons).
Connect the Mobius ActionCam to your PC or MAC, using the USB cable provided with it, and open the relevant GUI (Graphic User Interface) from the link given by russ331 above:-
http://www.mytempfiles.info/mobius/index.html
Import the above "SYSCFG.TXT" file into the GUI you are using and alter the
Video Mode Settings by ticking the box next to 'Rotate Video 180 Deg' settings. Save the resulting "SYSCFG.TXT" to your Mobius Micro SD card.
To load your new settings onto your Mobius ActionCam repeat the above button holding sequence on Page 9 of the instructions (i.e., Hold down Mode 'M' button & then also Power Button together until the top RED LED flashes 3 times and camera turns off, then release these two buttons).
Hopefully this will get the video the 'right way' up for the upside down mounting in your car.