I notice only minivans, SUV‘s, station wagons, and hatchbacks have rear windshield wipers, while sedans don‘t. Why? The snow and rain probably actually accumulates on a sedan‘s rear windshield because it‘s almost horizontal, so why don‘t they have a wiper? What is the need to have them on other types of cars anyway, if sedans don‘t?Also, I know some sports cars like toyota Celica and the acura one have a rear windshield wiper, but the majority of sedans don‘t.
The reason sedan don't have rear wipers is because of aerodynamics. The rear windows, which is like mostly vertical, doesn't get that much rain, because you're driving FORWARD. Very little water actually land on rear window. There's also rain-run-off channels on the roof of the car to guide the water away from the top of the roof, then out to the sides. The roof is actually curved, like the road. So most water don't even runoff to the rear windows. And another factor is the trunk itself, which helps move air along and not circling around the rear window, trapping dirt and rain. Air flows past the roof and flies for a bit then drops onto the trunk. There's a bit of a vacuum near the rear window, but not enough. Hatchbacks, with sharply raked windows, have much bigger surface area so rain can drop onto the rear window itself. There is also no 'trunk' to guide the airflow. All of the air flows right at the surface of the window, so it does need rear wipers. SUVs/wagons with window right at the rear has nearly vertical windows, but not the trunk to guide the airflow. It has a low-pressure zone right in that area when it's moving at speed, which will suck in water and dirt and thus make the window very dirty. Wiper's not for the rain, but rather for the dirt (so it also has washer nozzles) --- Kasey C, PC guru since Apple II days We have enough youth, how about a fountain of SMART?
Back in the day, vehicles like sedans and SUV's had wipers in the back for convenience but most places have bastard kids and gangs and all sort of trash. They would break them or removed them which cost a lot of money to replace, so the car companies thought of this Defoggers. These metal lines would transmit heat through the rear windows which will defrost windows and cause water to move. Then they notice it can be expensive just as well and perhaps dangerous which they stopped on most newer cars. Both these methods would make the cars even more expensive for a luxury that has been replaced with something cheaper. Air. They now put air vents by the rear of the car with a nob in the front to defrost windows either with cold or warm air. However, there are still companies that DO still install the metal strings on the rear and wipers too, but they not cost efficient so you'll hardly find them on newer cars. Though Vans, Trucks, and Station Wagons still have them installed or not.
