depends on the car...When I drove my parents SUV, I barely noticed a difference. In my car now...it's minimal, but I notice it. I'm with rg, though. I have black interior and would roast without AC in the summer. Fug that.
my xterra gets better mileage with the a/c compared to having the windows rolled down. . .but the difference is negligible. . .the difference in comfort is night and day. . .a/c wins. . .
same here...my mechanical purist father believed that the a/c components corrupted the design of a car's engine and put undue and unwanted strain, vibration and stress on the motor, made the car hard to work on...he resisted a/c equipped cars for decades....
his son learned early on to compromise his automotive principles...