What affects MPG the most?

I was driving home yesterday and turned off my air conditioning when I rolled my windows down.

The wind is nice.

Then I was wondering if it would be more fuel efficient to run the air conditioning rather than have my windows open which creates drag.

According to my mileage tracker/fuel efficiency calculator I am getting 16.23686 miles per gallon of fuel used with mostly highway driving and a moderate amount of air conditioning and window down driving.

Cast your votes!

 

does your current set-up include all of this
lift, armor, bumpers, and big tires

highway speed affects my MPG the most, the drop when running 75-95 mph seems significant but have never calculated it
i am sure that using A/C in stop and go idle is significant too, I usually roll the windows down after getting off the freeway and shutting the A/C down

 

No, it is a completely stock truck which has been concerning to me as I realized recently my MPG is so bad.

The truck is pretty new to me, I have put a couple hundred miles on it so far.

 

yes 16mpg is bad! ... i get more than 20mpg keeping under 75mph with no mods other than slightly larger tires than stock
we need to get you better MPGs!


what RPMs do you usually run it at?
also, check the tires for inflation levels, that has always had a significant impact on my mileage

 

also, check the tires for inflation levels, that has always had a significant impact on my mileage

 

I actually just had the psi taken down to factory specs. They were running 10 psi over what it calls for (26 front, 29 back). Now my tires look squishy and I don't like it.

 

i try to have 35psi all around, not sure why the factory specs are set at that level perhaps for a 'softer' ride?

 

Mostly stock 1st gen here. 2004 double cab, 265/75r16 on stock suspension (lifting coming this week).

I was getting about 15mpg when I got my truck. Currently I get 19-21mpg, tires are Copper ST Maxxs inflated to 32psi. The chalk test determined this was my ideal PSI for my setup. I live in a hilly area and have lots of downshifts for the first 10 minutes of my drive then mostly mixed stop and go the other 20 minutes.

Fuel filter, plus and a clean air filter did WONDERS for the MPGs and power delivery.

 

big heavy tires

 

I would say the first two options are like 1-2 mpg. Same as winter gas. Any more than that and the issue is elsewhere.

 

I noticed mine dip awhile back... I changed my plugs, and plug wires with OEM replacements and got back up to 18mpg consistently. I drive in the city a lot which prevents it from going higher than that.

 

have you found a buyer yet or you decide to keep your black truck?
we almost have the same angle shots in avatars now!

 

...it actually sold like two weeks ago.... i just keep hanging around TW. I like it here and am not ready to leave... and no one has kicked me out yet

 

very cool!

 

There are so many variables at play here I’m not sure this test can be validated unless you did it in a wind tunnel.

That being said, I believe the correct answer is “depends on how fast you’re going”

 

Windows down I get a pretty consistent 25mpg. With the AC on though, it's a different story - I'll get about 22. I attribute that difference to the 2.4 being underpowered. I had a 2nd Gen 2wd with the 2.7 that I could get about 27mpg in.

 

I've always felt that the A/C was more of a parasitic drain on the engine power versus the reduced aerodynamic efficiency of having the windows down.

That said, sometimes I say "to hell with it" and drive with the windows down and the A/C on.

 

in winters I like to drive with the heat on full blast and windows partway down in single digit temps
what a rush when i catch some of that cold Dakotas wind through the cab cannot breathe


the 4wd in winters does have an effect on MPG quite a bit

 

You need to add a third option. Side mirrors folded in vs out.