[Shotimes] Cold Weather MPG

[George Fourchy]

On Fri, 17 Jan 2003 23:55:30 EST, BJamesjr@aol.com wrote:

> I have mentioned 
>in the past how much better mileage I got on the interstates across New 
>Mexico than I get on the freeways around Dallas, and I was told that it was 
>due to different gasoline formulations used in the big city (Dallas) vs. what 
>they sell out in the middle of nowhere in New Mexico.

It's more the fact that you are up at 5 or 6 thousand feet, which is a quarter of
the way up into space, pressure wise, so the air is much thinner than down at 500
feet or so, like at Dallas.  Just like an airplane, you will use less energy to
maintain a given speed at higher altitudes, and the evidence of this will be more
mpg.  SHOs get in the low 30s up there going 80 mph, and Mustang 5.0s can get 29
mpg.   You
have less power, though.

Colder air is more dense, and in the case of aircraft, will result in a lower
cruising speed for a given power setting.  On the ground, the result of colder air
would be less mpg, since speed would be the same but more power would be needed to
maintain it, but a much less noticable amount than what is increased by the higher
altitude.

Us flyers use the ICE-T rule for airspeed, which corrects indicated a/s for gauge
error, temperature, and pressure to get true airspeed, which is the actual speed
over the ground.     ...more than you ever wanted to know!

Towing the Plus from Hell across I-40 from Ok City to San Francisco (in the summer),
the Crown Vic was able to get around 18 mpg at 65 mph.  Back in California, at a
couple hundred feet MSL, it dropped down to below 10.   Anything below 65 felt like
I was lugging the engine, and a lower gear felt like overrevving it.  CVs are not
the best towing vehicle for a load that big.   (obviously)

George