A Dictionary of Dream Symbols
by Eric Ackroyd(1) If in your dream you crash - in a car or train or aeroplane - this probably signifies that you are in a state of anxiety over some undertaking or situation.
(2) If you are driving, the crash may symbolize an unconscious desire to punish yourself. What guilt-feelings are you harbouring? Guilt and sado-masochism often go hand in hand. Dissolve the guilt-fee lings (which are almost certainly irrational and which, anyway, can contribute nothing of value to life - your own or anyone else’s), and the violence will dissolve, too.
(3) The crash may express a (hidden) fear of mental breakdown, in which case you ought to seek help.
Encyclopedia of Dreams
by Michael and Elizabeth ThiessenIf you hear a loud crash, such as the percussion sound of a drum or cymbals, that is a warning to calm your environment down in order to control your nerves.
For cars crashing, see wreck.