Downhill dream meaning is explained below using 2 different sources. Each interpretation is shown with its source.

Interpretation 1 — Ariadne Green

Traveling downhill may represent either an easy coast to your destination or that you are heading downhill in your profession, suggesting a loss in your financial worth.
Source: Ariadne's Book of Dream Author: Ariadne Green

Interpretation 2 — Klaus Vollmar

Letting go; fear of “going down” (to the depth of emotions, or sexuality, etc.) as in Falling.
Source: Little Giant Encyclopedia Author: Klaus Vollmar