Which is the more efficient way to cool my car, A/C or the windows?

23 August 2023

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Driving in summer, I can cool my car by using air conditioning or opening the windows. One drains the battery, the other makes the car less aerodynamic. Which is more efficient?

Graham JonesBridgham, Norfolk, UK

It would be much better to use the air conditioning rather than open the windows.

As far as I know, all car air conditioning systems are run directly from the engine, via a drive belt such as the one used for the alternator, water pump and power steering. A small amount of electricity will be used for the control mechanism, air blower and the …

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