Elevation and MPG

so i have been tracking my MPG on fuelly.com since i purchased my truck in southern california. in so cal, i was getting about 18-19 MPG with the best being over 20 MPG. within 8 months of owning the truck, i moved to colorado and, shortly after that, i put the lift and tires on it. when i did that, thats when i noticed the drop in MPG to 15-16 MPG (and sometimes 13 MPG). the elevation in colorado (at a minimum) is 5000 feet and when we went off roading, we got up to 12000 feet. i never considered the elevation change to be the cause of the lower MPG; i thought that it was due to the tires. so when i moved out to massachusetts, thats when it dawned on me that the elevation must have an effect on MPG. i am sure some of you are saying, "well, duh", but its just that i have the data now to back that up. 6 out of the last 7 fill ups in MA have been at 17-18 MPG. so it seems that i really only lost about 1 MPG due to the larger tires.
just thought that i would share

 

Interesting.

I'm at around 4000 elevation and used to live near sea level with no change when I moved.

But did notice a big drop in mpg a few years ago when ethanol was added to most of the gasoline. Probably 2-3 mpg drop.

 

When I go to Colorado my mpg goes up. All my best tanks were while visting the fam in Ft Collins and Denver.

Did you use 90 or better octane while in the mountains?

 

This is interesting, because when flying as you go up, air thins out, so you have to lean the fuel mixture and fuel economy gets better, to a point at least, then you just start losing power and fuel economy once you get too high, but at sea level it's noticeably worse with denser air, and more fuel to keep a good fuel/air mixture. I would imagine the same would apply to vehicles? or even in the summer?

 

Im at 5650 feet in Southern Utah and I have 35in BFG KM2 Mud terrains with stock gears getting 15.5-16 consistently. and i always put 87 not the 85 that they offer in the higher elevations.

 

no, i always used 85/87.

 

Could it be that Colorado is mountainous, requiring the engine to work harder going up and down all the terrain? MA and So. Cal are going to be relatively flat compared to driving I-70 in the mountains of Colorado.

 

Its the lift and big tires.Almost everyone who complains about MPGs has a lift and bigger tires than stock.If you want to play you have to pay!

 

I am no scientist but live up in Vail, thus driving in the mountains all the time. I have no idea how elevation effects mpg but grinding up and over mtn passes and what not has to have an effect. The engine definitely works harder in under these conditions.

 

You obviously didnt read his entire post. You need to read to succeed!

 

yes, good point. however, when i was in colorado, my daily commute (westminster to louisville) was through the same type of rolling hills as there are here in MA.
when i went off roading, i went through the passes and, yes, that would drop the MPG.

 

What about winter gas? The last feel ups for me have yielded much better mpg. Winter gas gas come to an end!!!

 

so odd.... i hit 19.4 MPG on my last tank.
http://www.fuelly.com/driver/NetMonkey/tacoma
87 octane, on 285's, and all back country/city driving.

 

2012 V6 DC auto: I live and work between 5,400'-9,000', 87 or 91 OCT, getting 19-21 mpg with stock set up. The lower values for me are typically when I use the truck in 4WD.

 

^^^This

Winter gas really demolishes your mpg.

I've filled up 50 something times here in Denver and can say with confidence, winter gas is awful. Look at my fuelly link below. I go from 21-25mpg in the summer to 19 if I'm lucky, in the winter.

And as others have mentioned, higher elevation = less dense air, thus less fuel is required to hit a stoichiometric a/f ratio (or close to it). Whenever I've traveled out of state, I've always noticed a slight decrease in gas mileage the closer to sea level I get.

 

I get better mpg in the Colorado front range and in the mountains than lower altitudes.

Thinner air is good for lower wind resistance and less power which means less gas. I get 35mpg driving 60 around Denver.

Driving in Mississippi at 60 I was lucky to get 28 mpg.

 

How does that negate? Less oxygen means less power and less gas.