What would decrease fuel economy worse, using AC or driving with windows down?
Posted by admin in Finance Sunday, 2 October 2011 07:17 4 Comments
I am taking a road trip (about 1500 miles) all of it will be on the high way driving 65-75 (posted speed limit) What will decrease my fuel economy more? Running the AC or having the windows open? My train of thought is having the windows down would increase drag decreasing the fuel economy. I know that the AC will decrease my fuel economy, but which one would make a bigger difference? Or is the whole theory of increased drag on the car with windows open just preposterous?
Studies have shown that driving with the windows down will cause sufficient drag to dramatically increase fuel consumption. While having the AC on, does the same, it has been shown to be more efficient than having the windows open.
i was told by my manic that over 55 mph use air the economy is better.
of coarse much under 55,and windows down don’t cool very well,so i use air all summer.
Hi James
I like your thinking
In truth the AC will make your engine use more fuel because of the loading. With the vehicle idling and AC off, listen to your engine or look at the tachometer (if fitted), now switch the AC on, most cars increase in revs because a sensor senses the load increase and auto ups the idle. Some earlier models may drop revs as they don’t have an auto idle up feature.
Driving along and you wind down all the windows (if you have electric fitted) do you notice a speed decrease or does it feel like the engine came under more load – not really. At 65 mph you will probably have your windows almost up due to the noise.
Have a good trip
with taking car in wind tunnels as part of the design and making A/C more efficient it really makes no difference