Why does hybrid's my miles per gallon ratio go down significantly when i use my ac?

The AC uses battery power, so while you have it running the engine must use gasolene power so that there is extra electricity for the AC.

Even having your windows down will use more fuel too – it will create more drag on the car. Best is to just have the fan going w/o AC

Even if you did not have a hybrid, the AC requires power and burns fuel faster.

Because using the air-conditioning burns fuel. Even people who have regular cars will turn off the AC if they are driving around looking for a gas station. Try running your solely on battery power, and then try running the AC.

Most people don’t know the AC uses 5 to 7 hp. No matter how you power it, it will still need those horsepower ratings. “There ain’t no such a thing as a free lunch”