(What follows is strident, but it is directed at the attitude among the FE conscious that A/C is somehow optional; not at the author of the quote)
You obviously don't live in a place where heat is a constant, nor have you dealt with heat prostration. Heat kill more North Americans than all other weather events
combined. And, as todays vehicle are not designed for ventilation the way they once were, the lack of A/C makes them hotter than in decades past.
I submit that if you
worked in a vehicle in the hotter parts of the U.S. that you'd find this premise foolish.
Safety when behind the wheel has much to do with being alert. Being drowsy, groggy, hell, just plain sweaty isn't any form of being alert . . where one sweats through his clothing numerous times per day.
There are outdoor jobs advertised here where a
requirement is that one is already employed in an outdoor position. The cull is only partly for those who find it uncomfortable.
The control for being cold is easy: add clothing. There is no such e-z control for high heat & humidity.
Let's also, for safety's sake, add in the ability of A/C to greatly reduce dust and other irritants, as well as greatly reduce sound levels. These both wear down any driver quickly. So . . . temps of 90+, high humidity and heavy unavoidable dust. This is no extreme state confined to one area or only a few occupations.
Let me also add that it assumes one will never be old, injured, ill or distracted. Any combination of those, and, in the heat, one will simply not drive (if one is at all smart). A/C is a
lifesaver in a larger sense.
No, for A/C, it is better to investigate the operation of components and the system as dealer-spec is often "off". We have all heard of "tolerance stack" and in proper A/C operation, IMO, consider it a given that there is something in even a brand-new vehicle's HVAC system that warrants tuning.
The best A/C is the one whose compressor operates for the shortest times; and the blower at the lowest energy draw. Knowing "how" to use it is just as important for longest term efficiency. (Think of this as improvements to rolling resistance, where use is likened to aero penalties; as shorthand). I touched on it in
this thread.
HVAC use in a vehicle has to be factored for an enclosed vehicle on the highways, no differently than for cold weather warm-up.
For most of North America there are only a few months of the year where temps are "ideal" from this perspective of FE.
Thus my earlier question about "prediction": vehicle spec first, climate & terrain second, and driver use plus driver skill afterwards are the major determinants . . but is there a short-cut about temps? Vehicle logging seems to be the singular answer (given adequate warmup -- which I posit as being 30-miles, minimum, for any vehicle). Past that, past those, perhaps we can start to make more general statements on weather data.
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