fuel economy v engine temp

[Pottree@domain.elided]

I think I recall correctly that Fred di once stated an engine running HOT 
would be more efficient in fuel use.

I just returned from a 600+ mile trip in the GTV6 which afforded a lot of 
great driving experiences, mostly in our local So. Cal. deserts.

This is a beautiful time of year in the desert.  For those who think of 
deserts as scorchingly hot places where there is nothing but blowing sand and 
Rudolph Valentino on a camel -- well, that image is not even close to true 
around here!

This jaunt (combining business and pleasure) took me to three different 
deserts: the low desert around Anza Borrego, which is mostly at our below sea 
level; the Palm Springs area; the high desert around Joshua Tree.  Weather 
was substantially the same at all the elevations, with daytime highs around 
80F and nighttime lows around 45F.

The GTV6 is typically a cool-running car, even w/ the A/C on -- as long as 
it's moving; idling for a long time in heavy stop-and-go traffic in hot 
weather makes a big difference, and a lot of idling in very hot weather will 
cause the car to get too hot if the A/C is on.  Luckily, traffic wasn't an 
issue on this week's trip, and the A/C was rarely even needed.

The desert also tends to have a lot of wind, especially in the area just 
outside Palm Springs, where there is a huge wind farm, where hundreds of 
giant windmills generate electricity that's pumped int o the local power 
grid.  This is WIND: I saw a 50' mobile home (the type used for temporary 
space such as construction site shacks) flipped off the road and onto its 
roof by the side of the road).

Part of my trip involved driving straight into this strong wind.  Although 
the ambient temp was warm (around 80F) and I was going a good clip (around 70 
mph, as fast as I dared, given conditions), and even had the A/C on (windows 
and sunroof had to be closed against blowing sand and small motorcycles, 
etc.), the wind boring straight in to the engine bay lowered the water temp 
to what I guess to be around 125F (just before the first tick on the gauge 
which appears to represent about 150F, with the mid tick marked at 175F).  

If the engine is more efficient when quite hot, does this mean that the wind 
dropping the temp would decrease gas mileage?

Charlie
LA, CA, USA

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