So in today’s post about auto A/C (with it’s interesting, if sadly unsurprising result) you missed a part of the A/C question that I would have liked to see answered.
The poster was from Tuscon, so in terms of relevance to him/her/it having the A/C running full blast seems appropriate. But for those in more moderate climates, I would wonder how variable-volume A/C compressors change the equation. The idea (or so I gather) about them is this: if you only need to cool the air inside the car a few degrees, you need less oomph from the A/C compressor than you would if you need to cool it by 20+ degrees, so it reforms itself to use less than its maximum capacity rather than running full blast for a while, switching off for a while, running full blast for a while longer, etc. In the owner’s manual for my 1993 Audi, one of the selling points for this was more efficient operation (it had a little tree next to it and everything - the tree signifying how much Audi cared about the environment. Eh).
I live in Houston, which is as close to hell as it gets, so I’m not sure I could provide any helpful real-life data about A/C operation in moderate temperatures. But I would be interested to know if in general, the idea is sound, or if it’s just car manufacturer malarkey.