The 42065 RC Tracked Racer is a nice canvas for modding.
I was a bit disappointed when I found that it didn't have any technic gears apart from what you find when you disassemble the motors. Technic has always been used to teach mechanics to kids, and I personally find differential drive to be a super interesting alternative to the direct drive approach.
It didn't take more than a couple of hours to stuff in a couple of differentials, so I made a little video of this mod in action:
Another obvious "MOD" is to SBrick the model. This is a ridiculously simple MOD, so I decided to document the whole process of unpacking, updating, and programming a remote using the SBrick:
I also had super high hopes for the L-motors. Perhaps this would be more interesting with a 2:1 gearing for double speed. This is how the standard direct-drive model performs with L-motors:
Next up will be a GBC-module built mostly from parts of the model. To make a plain belt drive module is not really interesting anymore, so I'm currently trying to figure out if it can be made more interesting.