If you were washing yourself, then such dream could have negative and positive meanings depending on the situation in your waking life and the way you felt during the washing. If you were washing yourself to get rid of all the dirt, then it signifies the negative emotions you are trying to wash away. If you washed yourself and felt well about it, then it shows how happy you are because of all the aspects in your life. If you were washing your car, then it means you are ready to move forward in your life full of energy and potential.
Read more about dreaming of Washing in other dream meanings interpretations.