Why is there a hump in the middle of the back row in some cars?

[SkylarLynn]

Some cars have a hump in the middle of the back row because: for the flatness of the chassis, as the car's underbody is equipped with an exhaust pipe or drive shaft, usually rear-wheel-drive cars must transmit the engine's power to the rear wheels through the drive shaft, so structurally, such a hump is necessary. The hump between the front and rear seats from front to back is a structural design intended to enhance the longitudinal rigidity of the cabin, while also providing space for the exhaust pipe to run backward without affecting the chassis's ground clearance. If the chassis were a flat steel plate, it would easily "fold" upon impact. However, if the chassis is designed with a semi-circular hump, its ability to withstand impact can be many times stronger than a flat steel plate, and it is less prone to deformation. This is similar to adding a steel beam to the chassis.