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If you have ever carefully observed the different vehicles running on the roads, then one thing must have come to your mind. Most hatchback and SUV cars have a wiper installed on the rear windscreen, but this feature is missing in luxury and premium looking sedan cars. In such a situation, many people think that perhaps companies do not provide rear wiper in sedans to save money or reduce costs. But the reality is completely different from this. There is a huge technical and scientific reason behind this in automobile engineering. Let us understand it in very simple language.
1. Aerodynamics and car design
The main reason for the absence of rear wiper in sedan cars is Aerodynamic Design Is. Sedan cars are designed in a ‘three-box’ style, with the engine, passenger cabin and boot space (deck) located at different angles. The rear glass of these cars goes downwards like a smooth slope (Sloping Roofline).
When a car runs on the road at high speed, the air coming from the front passes through the roof of the car and over the rear windshield in a very fast and straight stream. This strong flow of air automatically takes away with itself the light dust, soil and rain drops falling on the glass. That is, the natural wind does the work of keeping the rear glass of the sedan clean.
2. Why is rear wiper necessary in SUV and hatchback?
The rear profile of SUV and hatchback cars is completely straight or flat (Flat Vertical Back). When these vehicles travel at high speed, due to their straight design the air pressure immediately behind the vehicle suddenly drops, causing a Low-pressure vacuum zone (Low-Pressure Vacuum Zone) is formed.
Due to this vacuum, the dust, mud, dirt and rain water flying from under the car and from the wheels rotates backwards and gets stuck directly on the rear glass. Due to this, the driver stops seeing the traffic behind through the rear view mirror (IRVM). To clean this dirt, it becomes technically mandatory to provide rear wiper and washer in hatchbacks and SUVs.
3. Boot Space (Dicky) and Wiper Motor Replacement
There is also a practical reason that the boot space of sedan cars starts just below the rear glass. To operate the rear wiper, a heavy electrical motor has to be installed. In hatchbacks and SUVs, this motor is easily fitted inside the tailgate. But in the sedan, due to the trunk lid being located just below the glass, there is not enough and proper space to install the wiper mechanism and motor.
Is the objective of companies to save money?
It is completely a myth that companies do this to save money. Automobile companies give priority to aerodynamics, weight balance and fuel efficiency while designing vehicles. When the design of the car itself is capable of keeping the windshield clear, adding a rear wiper unnecessarily would increase the cost, weight and technical complexity of the car. This is the reason why rear wiper is not provided even in luxury sedan cars worth lakhs of rupees.