Driving off a cliff stands for a sudden loss of footing, a choice or situation that feels like it has gone over the edge. It is read as fear of failure or of a point of no return, not as a warning of harm.
When this appeared in your dream, what were you feeling?
My Cosmic Code has a private dream journal. Write a dream down and the app picks out the symbols in it, shows what dream books say about them and, over time, which words recur across your entries. The journal is stored on your device only.