Why is there a hump in the rear seat?
2 Answers
The reasons for the rear seat hump are as follows: 1. To increase the height between the car chassis and the ground. The chassis of a family car cannot be too close to the ground, as it would threaten driving safety. Early German car manufacturing used a beam structure, which is crucial for maintaining the integrity of the car body during collisions, thereby protecting passengers inside. Due to the nature of the beam structure, the middle of the rear seat has a hump. 2. To accommodate the exhaust pipe and drive shaft, the rear seat of a car needs to have a certain hump. Most family cars are front-wheel drive and lack a drive shaft mechanism, so some cars do not have a hump in the middle of the rear seat. However, rear-wheel drive and four-wheel drive vehicles must use a drive shaft to power the rear axle, and the exhaust pipe also needs to pass through the middle of the chassis. A groove is designed to accommodate the drive shaft and exhaust pipe, which strengthens the chassis's rigidity and improves the overall safety of the vehicle. The hump in the middle of the rear seat makes the car's layout more reasonable and the chassis safer.
The rear hump is primarily designed for the drivetrain system. In rear-wheel-drive or all-wheel-drive vehicles, it houses the driveshaft, which transmits power from the engine to the rear wheels. Without this hump, the driveshaft couldn't be installed, leading to ineffective power delivery. Additionally, it enhances the overall body rigidity, making the car more stable during turns or on rough roads and less prone to deformation. Some vehicles also use this space to route exhaust pipes or wiring harnesses, protecting them from damage. After studying numerous models, I've noticed the hump height varies by brand—for instance, BMW's rear-drive cars have higher humps, while Toyota's front-drive models are nearly flat. Although it compromises foot comfort for middle-seat passengers, this design represents a critical trade-off between performance and safety that engineers must carefully consider.
