On Thu, 20 Jul 2017 18:14:06 -0000 (UTC), Mad Roger
wrote:
On Thu, 20 Jul 2017 08:58:28 -0400,
Ed Pawlowski wrote:
Fuel-Economy Face-Off: Driving With Windows Open or With A/C Running?
http://www.consumerreports.org/fuel-...or-ac-running/
By Consumer Reports, June 18, 2017
Q. Does a car use more gasoline when you drive with the windows rolled down
or the air conditioning turned on?
A. ´We found that on an 85-degree day, running the A/C can reduce fuel
economy by 1 to 4 mpg, depending on the car....[while] the effect of
opening the windows at 65 mph did not measurably reduce fuel economy,¡
I'm not doubting their test results but that sounds like a broad blanket
statement. What particular car and engine? Will you get that result
with a Tesla, F-150 and 1987 Chrysler Cordova?
Both AC compressors and auto aerodynamics have improved over the years.
In any case, if it is 85 degrees, I'll have the AC on. My present car
has the best AC of any I've ever had since my first car with ac, a '68
Olds Vista Cruiser I bought in 1971.
That article was published *today* in the print magazine (it says), so, we
can presume they used a recent model year vehicle - but maybe more is in
the print article. (Anyone have it handy?)
The first line of the online version I quoted says they tested lots of cars
though...
"Weve tested this at various temperatures with multiple vehicles,€? says
Jake Fisher, CRs director of auto testing "
BTW, there were quite a few articles on the net which said the same thing.
So if you want to beat up the CR article, I can show you plenty more which
say the same thing that you'll also have to beat up. 
BTW, most people trust their own intuition more than they trust facts to
the contrary, so you might be surprised when you read the part about what
they found out when they tested cars that SAID to use high octane fuel, but
CR tested them with the low-octane (regular) fuel instead.
http://www.consumerreports.org/cro/c...nomy/index.htm
Under some conditions, ie. high temperature,and heavy load, the 2 cars
referenced will detune due to mild detonation on regular gas. Rhis
WILL cause a (possibly small, but measurable) decrease in power output
and fuel economy. It will not show up much on thir tests, but load the
car to capacity and drive up independence pass, or any other long hard
grade and it WILL be noticeable.
The difference between "premium recommended" and "premium required"
is "premium recomended" can compensate for low octane by detuning and
not cause any damage, while "premium required" cannot compensate
enough. Under "normal" driving you may get away with regular gas on
either car