<P> Air - conditioning for automobiles came into wide use from the late twentieth century . Although air conditioners use significant power ; the drag of a car with closed windows is less than if the windows are open to cool the occupants . There has been much debate on the effect of air conditioning on the fuel efficiency of a vehicle . Factors such as wind resistance , aerodynamics and engine power and weight must be considered , to find the true difference between using the air conditioning system and not using it , when estimating the actual fuel mileage . Other factors can affect the engine , and an overall engine heat increase can affect the cooling system of the vehicle . </P>
<P> Air - conditioning for automobiles came into wide use from the late twentieth century . Although air conditioners use significant power ; the drag of a car with closed windows is less than if the windows are open to cool the occupants . There has been much debate on the effect of air conditioning on the fuel efficiency of a vehicle . Factors such as wind resistance , aerodynamics and engine power and weight must be considered , to find the true difference between using the air conditioning system and not using it , when estimating the actual fuel mileage . Other factors can affect the engine , and an overall engine heat increase can affect the cooling system of the vehicle . </P>
when did air conditioning became standard in cars
when did air conditioning became standard in cars
late twentieth century
late twentieth century