Dreaming of a backseat suggests that you could be feeling that you are not quite in control of an aspect of your life. Being stuck in the backseat of a vehicle and unable to change your position indicates that it may be time for some internal inquiry. You may have eagerly handed over control of your life to somebody else, but are now resenting them for it.
[1]1. Feelings of being out of control, at the mercy of fate or the person driving.
2. Feelings of unimportance, being secondary.
3. Feelings of being picked on, dominated (as in “backseat driver”).
[2]Seat of submission; see “automobile”
[3]