What is the bulge in the middle of the rear seat of a sedan?

[VanAnthony]

The bulge in the middle of the rear seat of a sedan is designed to maintain the flatness of the chassis. Since the underside of the car's chassis accommodates the exhaust pipe or drive shaft, rear-wheel-drive vehicles typically require a drive shaft to transmit power from the engine to the rear wheels, necessitating this structural bulge. Below are specific details on the related content: 1. For rear-wheel-drive vehicles, the middle section needs to house the drive shaft. The front-mounted engine transmits power to the rear wheels via the drive shaft. If the drive shaft is too low, it may lead to scraping the ground, affecting the car's ground clearance. Raising the vehicle height would compromise the car's center of gravity. Therefore, a localized raised floor is designed to protect the drive shaft while enhancing the car's stability, ground clearance, and handling. 2. If the car has a low chassis design and is front-wheel-drive, the middle bulge may serve as space for the exhaust pipe layout. 3. Even if the car is front-wheel-drive, the chassis might be built on a rear-wheel-drive platform or shared with higher-end models (rear-wheel-drive platform), resulting in the middle bulge in the rear seat.