<P> Most competing systems used a separate heating system and an engine - mounted compressor, driven by the engine crankshaft via a belt, with an evaporator in the car's trunk to deliver cold air through the rear parcel shelf and overhead vents . General Motors made a front - mounted air conditioning system optional in 1954 on Pontiacs with a straight - eight engine that added separate controls and air distribution . The alternative layout pioneered by Nash "became established practice and continues to form the basis of the modern and more sophisticated automatic climate control systems ." </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> <P> The innovation was adopted quickly and new features to air conditioning like the Cadillac Comfort Control which was a completely automatic heating and cooling system set by dial thermostat was introduced as an industry first in the 1964 model year . By 1960 about 20% of all cars in the U.S. had air - conditioning, with the percentage increasing to 80% in the warm areas of the Southwest . American Motors made air conditioning standard equipment on all AMC Ambassadors starting with the 1968 model year, a first in the mass market, with a base price starting at $2,671 . By 1969, 54% of domestic automobiles were equipped with air conditioning, with the feature needed not only for passenger comfort, but also to increase the car's resale value . </P> <P> A car cooler is an automobile evaporative cooler, sometimes referred to as a swamp cooler . Most are aftermarket relatively inexpensive accessories consisting of an external window - mounted metal cylinder without moving parts, but internal under dashboard or center floor units with an electric fan are available . It was an early type of automobile air conditioner and is not used in modern cars relying on refrigerative systems to cool the interior . </P>

When did air conditioning became common in cars