1.0.7 - PC - Steam - Mouse/keyboard
I'm having the same issue myself with the drill. I have tested each vehicle and they all do the same thing. No amount of speed helps either. Upon activating the drill, the vehicle almost immediately stops and starts sinking. Even with/without trailers. It will continue to sink until it falls through the ground into another cave system. Now when I have a buddy join my session, my game immediately drops frames to 10-12fps, (but I know they are aware of that glitch/issue). But when a buddy is in my session, his vehicle/drill work flawlessly without constantly sinking. He is like a freaking dolphin going in and out of water. No matter what I tried, I couldn't get mine to work even once he left the session and I would reset my game. Its seriously frustrating. Are the developers aware of this issue as well? I didnt read anything on it in the notes for the last update.
Edit - Does the same regardless of which drill (1, 2, or 3)