Lots of EOC, block heater and partial grille block even in summer. Today I hit 60 mpg within 2.5 miles of my garage. Local route knowledge honed for 50 years with an ultra gauge, 50 psi in the tires. Even the construction zone on I 64 (going to 3 lanes) with a 55 mph limit provides me with perfect downgrades and big rigs to break the air. I can even get to 60 mpg going 60 mph or a little less.
I generally don't turn on the AC until it hits lower 90's here unless the humidity is high or the wife is complaining. Then I hypermile the AC, using the compressor primarily when forced to decelerate. Always recirculate, low fan speed, compressor off except for short bursts when the mpg penalty is minimal.
I remember when they came out with these newer AC units in cars. I take it was with the different coolant they use now.
They said then, they had gotten the load on the engine down to less than driving with the windows open.
It's true, a modern ac unit should use about 5% of fuel if used constantly, maybe less. If you have ECO mode in your car, it will use a lot less as I've noticed my ac isn't as cold in ECO mode unless coasting.
A lot of cars now have scroll compressors. As the temperature in the cabin gets closer to the target, the compressor exerts less drag on the engine. Once you get the cabin cooled down, the compressor uses very little energy.