gas milage and AC

[laldog]

So far you guys were right.
My new (to me) ST kicks ass. It drives like any of the BMWs I've owned and is still the truck I need for other work related duties.

My next question is about gas mileage. I'm getting only about 12 mph which is disconcerting because about half of that was ON THE HIGHWAY!!!

How much does AC impact gas mileage?

I am way paranoid about my.transmission. Does poor gas mileage relate to possible transmission problems???

 

[GreenMando]

I get 27 mpg at 55 mph.
I get 25 mpg with AC at 55 mpg.
Your results will differ!

 

[Tech By Trade]

Try resetting your gas mileage once you get on the highway. They are horibly incorect unless you reset them when you fill up. Mine is realy close to my GPS and my calculations. I get around 26 on the highway lately as well.

 

[JohnnyO]

I reset the mpg thingy at every fillup. Most of my driving is in town with a little bit of highway and I average 14 to 15 mpg on each tank most of the time. It is very hilly here and on the highway I will get 20 to 22 mpg if I keep it under 70.

The tranny shouldn't affect your mpg as long as it is working properly.

On the highway because of wind resistance I think you will get better mpg with the A/C on and the windows up than you would with the A/C off and the windows down. These things aren't gas mileage champs no matter what you do. I picked up 3 mpg with the cat-back exhaust if you don't mind the noise (my wife hates it). It is rated at 19 highway.

 

[Tech By Trade]

A thought did come to mind about this. Keep an eye on your tach, see what your revs are at when you are driving. I know on my way to work there is a stretch of road that is 90kmph, and my truck was just on the border between 4th and 5th if I wasn't speeding. It would rev around 2500 when Driving that stretch of road. Once I figured out what was going on I kicked it down and it would switch in to 5th when I let off. Now the ECU figured out what is going on I guess because after a week or so now it is in 5th on that stretch of road. now she is under 2 for better mileage.

 

[GreenMando]

When I cruise at 55 my tach is reading well below 1500.