Women use air conditoners I roll the **** window down ill sweat before i have to put an extra unncessary work load on my engine and so will my g/f. I actually was testing out the air resistance yesterday and if you put your hand and arm out the window at 60mph on a 85 degree day and a 30 degree day you can feel the difference and im not talking about the temperature.
NO!!! Do not do this!!!!!!

It has been proven in mythbusters and countless articles. If you are over 50 mph, rolling down a window in favor of air conditioning is WORSE on your fuel economy, let alone uncomfortable. You are also severely overestimating the impact of A/C on your engine. It is a minor unnoticeable load in everyday driving. The effect of A/C on the engine also depends on the car as well. The 2000 Natural Gas Honda Civic I used at work was sluggish and the air conditioner made climbing hills impossible. However, the Cruze has plenty of torque, and on the highway you are constantly in the peak torque range, even though you only need a small fraction of it to maintain speed.
Last time I was at the drag strip, I actually did a run accidently with the air conditioning running. I did another run with it turned off and guess what... No change - both 15.8 @ 87 mph. If the load it puts on your engine was significant, it would noticeably affect horsepower. The effect would be much more pronounced on the track where any little thing will affect your time.
91 will probably make a bigger difference as the weather gets much hotter.
It won't be noticeable until you approach 100 degrees. At least, I never noticed it in last summers 90 degree heat. The hot weather MPG comparisons were in 100+ degree heat out west. 91 Octane at that point helps, but there are more important things going on at that point like heat soak causing the ECU to cut horsepower.