Stupid Fuel Mileage Questions

[frito-bandito]

Alright, thanks to hearing results of a study on the radio last night about MPGs, I want to know everyones thoughts on a couple of questions.

First, do you use more gas while running the AC, compared to causing drag by having the windows down at speeds above 45mph?

Secondly, does it actually save gas to ride with the tailgate down?

My theroy has always been, AC=makes engine work harder=more fuel consumption
And tailgate down = less drag= less fuel consumption.

But I never figured drag caused by having the windows down into the equation.

So what do y'all think, is ac better than windows down for MPG and tailgate up or down?

 

[shelbyt.67]

Tailgate up. Mythbusters proved it. Actually I havn't seen much if any mpg difference with A/C on or off. I seem to get about 15-16 no-matter what I'm doin.

 

[redneckchevy90]

yes leave the tailgate on and up. as far as the A/C I'm not really sure as mine is out of refrigerant. I can honestly tell u on the smaller cars with a 4 Banger it does effect the gas mileage. I had a 2k neon bought it with 13k miles. without the a/c running I got 33 highway,with it I got 28. so I don't know how the a/c effects these V8s

 

[DRAGGIN95]

I also get 15-16 all year long no matter what the temp is and no difference with or without ac in all of my 2wd gmt 400's, Also I seem to get the same mileage from a TBI 350 as I do from a vortec 350.

 

[ndians68]

It is better to go windows down until 60mph is when it evens out, and not longer is in the question.

 

[am92]

Yeah, with the tailgate up it creates a "bubble" in the bed of swirling air and then makes the airflow transition from the roof to the tailgate smooth. If you ever get leaves in the back of your truck and drive down the highway you can see the swirling air pocket, it's pretty cool.

 

[frito-bandito]

Thanks guys, I see now that I was hurting my mileage more than helping it.

 

[pike_mazter]

I don't run my A/C much but when I do I don't notice any difference.

I have a tonneau cover and I can't tell a difference in MPG when its opened or closed.

 

[1993GMCSierra]

Honestly, I'd think the drag with the A/C on is equal to driving at speeds above 45 with the windows down. Of course, with A/C you have the advantage of it being cool inside, vs. nearly ambient temp.

 

[frito-bandito]

Well, since I posted this , I've rode with the tailgate up and the ac on, and I haven't noticed any mpg difference at all. This is great, it is nice being able to drive to work with the air on and not be already sweaty when I get there. Thanks for the input fellers!!