i was wondering if running the air conditioner will make my gas mileage worse i have heard from people that it makes no difference but when i had my 95 civic when i turned the air conditioner on it would run the engine at around 1000 rpms more than usual and felt much slower than usuall maybe it is different with new cars. so the questions are:

will my cars mileage become worse while running the a/c ?

will my car be slower when the a/c is running?

and im pretty sure the a/c system will last longer the less u run it

 

When I have my A/C on, I can feel a slight loss in acceleration; even with the S/C. Given this, I would expect to lose a couple of MPG with the A/C on. Although I haven't actually tested this.

 

The a/c compressor, when engaged does place a drag (some say abour 3hp) on the engine so yes you will lose some mileage and performance. I keep records of mileage at each tank and only notice about 1-2mpg drop if I use it (depending on how much). Overall I average 29-30 so its not much of a loss for me.

 

Don't forget the A/C compressor will automatically shut off once/if you go wide open throttle on the engine.

I read somewhere that driving with the windows down actually uses more gas, due to wind resistance, then if you have the A/C on.

 

Really, I wasn't aware of that. Is this in the manual? However, I do feel a slight loss in power with the A/C on.

Makes sense...

 

If you get over a particular speed, the aerodynamic drag will be greater than the A/C compressor loss. If it's cool out and you want to save $$$ on gas, turn the temp up so the compressor goes off or just use the vents with the windows up.

The road speed where "A/C better than windows down," is going to be different for different makes and models of cars.

 

It all depends whether you're doing city driving or highway driving. Driving all freeway nonstop from full tank to 1/4, I got 32 mpg with the A/C set to 74 the whole trip. Combined city/hwy driving brought the average to 22-24 mpg. City-alone driving ended up at 17-18 mpg.

 

Using the a/c, all other factors remaining equal, will result in lower gas mileage (estimates range from .5 to 3 mpg depending on the vehicle).

Also, technically, using the radio (or any other electrical device in the car) will also lower gas mileage, although this loss is very small (like maybe .0001 mpg )The energy to run these devices must come from somewhere, and the generation of this energy requires fuel. Since this is such a small amount, it won't be noticed...

 

This is why i'm getting 17-19mpg. I always drive with the windows down and the radio up.