What is the raised section in the middle of the car's rear row called?
4 Answers
Sedan rear row middle raised section is to maintain chassis flatness. Since the car's underbody chassis has exhaust pipes or drive shafts, usually rear-wheel-drive cars must transmit engine power to the rear wheels through the drive shaft, so structurally this raised section is necessary. Below are specific introductions to related content: 1. The car adopts front-engine rear-wheel-drive layout: The middle section needs to accommodate the drive shaft. The front-mounted engine transmits power to the rear wheels through the drive shaft. If the drive shaft is too low, it may easily scrape the ground, affecting the car's passing ability. If the body height is increased, it will affect the car's center of gravity. Therefore, the local floor needs to be made into a raised shape to protect the car's drive shaft and improve the car's stability, passing ability and handling. 2. The car chassis design is relatively low: The car may be front-wheel-drive, but needs to pass the exhaust pipe, so the middle raised section provides space for exhaust pipe design. 3. The car is front-wheel-drive: But the car chassis uses rear-wheel-drive platform, or shares a platform with its own high-end models (rear-wheel-drive platform), resulting in the raised section in the middle of the car's rear row.
I've been driving for many years, and that hump in the middle of the rear seats is generally called the driveshaft tunnel or center tunnel. It's mainly designed to provide space for the drivetrain and exhaust system. When designing a car, to transfer power from the front to the rear wheels, a driveshaft needs to run across the underbody, and the exhaust pipe is also routed underneath. To avoid compromising ground clearance, this raised section is formed. It's especially noticeable in rear-wheel-drive models, like older BMW or Mercedes-Benz cars, but front-wheel-drive vehicles usually have a flatter floor due to their different structure, as the drivetrain can be placed directly under the front-mounted engine. This hump isn't very passenger-friendly—the middle passenger has nowhere to place their feet and has to sit with legs apart, which becomes uncomfortable over time. In reality, this design is reasonable as it helps lower the car's center of gravity for better stability and reduces deformation risks during collisions. However, manufacturers are now working to optimize it. For example, electric vehicles don't need a driveshaft, allowing for a completely flat floor and more spacious interiors.
As a passenger often squeezed in the back seat, that hump is really annoying. Everyone calls it the central bulge or rear tunnel. I think its existence is necessary because the driveshaft and exhaust pipe need to pass underneath the car. Without the bulge, the car would have a higher chassis and feel unstable when driving. It's common in both SUVs and sedans, such as in family models like Volkswagen. During long trips, the person in the middle position may experience knee pain from pressing against that hard bulge. Manufacturers aim to improve this by adjusting the layout or using new materials to reduce the height of the bulge, but it can't be completely removed as it would affect the overall structural strength. I’ve also heard that some high-end cars use intelligent chassis designs to better conceal this feature without compromising comfort. The key takeaway is to remind everyone to avoid sitting in the middle seat when in the back and prioritize the side seats for more comfort.
The raised section in the middle of the rear seat is called the central tunnel, primarily designed to accommodate drivetrain components. In automotive architecture, the power transmission path from the engine to the wheels requires space for components like the driveshaft or exhaust pipe to pass through, with this raised section protecting them from road debris. Rear-wheel-drive vehicles such as the Toyota Crown feature a prominent hump, whereas front-wheel-drive models like the Honda Civic have a much flatter design. Although this protrusion compromises rear passenger comfort, it enhances body rigidity and helps distribute impact forces during collisions for improved safety. Modern vehicles are gradually optimizing this feature—for instance, electric vehicles eliminate the driveshaft, resulting in a flatter rear floor.
