If you are hovering in the middle of a car and your not touching anything like your just floating will you go with the car or hit the back of the car?

Something has to exert a force on you to change the speed
you're moving at or the direction you're moving.
If you're hovering, then there's no force acting on you.

-- If you started hovering before the car started moving:
Then when the car starts moving, you won't start moving,
and the seat will come up behind you and hit you.

-- If you were already seated and moving before you started hovering:
. . . Then you'll move with the car as long as the car keeps the same speed
in a straight line. 
. . . But if the car speeds up, the seat will come up behind you and hit you. 
. . . If the car slows down, you'll go forward and hit the windshield.
. . . If the car goes onto a curve or turns a corner, you'll keep going straight
and hit the side of the car.