Thursday, 20 November 2014

Windows down vs AC on: what is more fuel efficient?

To roll down your car windows or not – this has been a hotly debated topic, perhaps, ever since car air-conditioners came into existence. Popular belief is that driving with the windows down saves more fuel than rolling them up to turn on the air conditioner. However, an alternate theory posits that driving with windows down hogs as much fuel due to the drag, or the air resistance, it creates on the car. Drag is caused when air enters the car through the windows instead of flowing over it. More power is used in combating this drag, which in turn, burns more fuel. 
power window
So how does one get around this conundrum and what really is the right practice to save fuel? While it’s true that air-conditioners consume a lot of fuel, you’d be surprised to know that a study by US-based Society of Automotive Engineers (SAE) found that driving with the windows up and AC on is more fuel economical than driving with windows down!
 In fact, their tests showed a 20 percent reduction in mileage with the windows rolled down. With the windows up and AC on, fuel efficiency dropped by just 10 percent. Of course, these results vary depending on the type of car (an SUV experiences higher drag than a small car), how aerodynamic it is, outside temperature, wind speed, etc. 

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