DODGE RAM FORUM - Ram Forums and Owners Club! - Dodge Truck Forum

DODGE RAM FORUM - Ram Forums and Owners Club! - Dodge Truck Forum (
-   Fuel System (
-   -   Robbing MPG? (

2001RAMSPORT 02-02-2011 06:06 PM

Robbing MPG?
Just a quick question.

Is it true that leaving the A/C and Heat on in the truck steals some mpg?



erm 02-02-2011 06:09 PM

A/C yes as you have to drive the A/C compressor off your accessory drive belt and it creates resistance, requiring more power to turn the engine.

huntergreen 02-02-2011 06:12 PM

"back in the day", many would say a/c used up 1 to 2 mpg. then tests wre done and it was concluded that driving with windows down used more mpg do to drag on the car. never read a study, this all here say from "old motor heads from the sixties. i am sure turning the compressor uses a little mpg. i don't see how heat would.

2001RAMSPORT 02-02-2011 06:14 PM

Thanks so if i run the a/c it is the same as taking the compressor off?

Ram15002ndgen 02-02-2011 06:33 PM

Heat is free energy given off by the motor, no power robbed at all, UNLESS you are running the defrost mode since that will kick on the A/C compressor. A/C will rob some power as you are adding more drag to the motor by running the compressor, but in 100* heat it's worth it. Remember to turn off your A/C when you turn of your engine, it's not good to leave it on ALL the time.

Poriggity 02-02-2011 07:02 PM

In my experience, driving with the AC on does not negate fuel mileage much, if at all. It certainly does not hurt MPG enough that I think I should go without it! I like to be comfortable while I drive, and darn the circumstances of lost MPG!

wester399 02-02-2011 10:44 PM

i never use it in the city i always go windows down I have heard it does hurt mpg however the drag created on the highway would for sure be enough to give the same affect i would think. I always run it on the highway tho on hot days cause windows down is just too windy for this guy.

2001RAMSPORT 07-07-2011 09:06 AM

Actually Mythbusters did a test and driving with the windows down is more fuel efficient.

erm 07-07-2011 12:42 PM

And who wants to do that ^^^^ on a HOT summer day??? :D

dwadestrick 07-07-2011 01:49 PM


Originally Posted by MADDOG (Post 563550)
And who wants to do that ^^^^ on a HOT summer day??? :D

Not me. High today 90 F with heat index of 95 F and humidity of 70% and no rain.

All times are GMT -4. The time now is 07:48 PM.

Powered by vBulletin® Version 3.8.9
Copyright ©2000 - 2015, vBulletin Solutions, Inc.
= Copyright a Network Site =Ad Management by RedTyger