Elevation and MPG

Well, I just made 20.4 mpg on 91 oct running from Littleton, CO down south on I-25 to 24 west then up to Tarryall and Jefferson, then back to Littleton on 285S to 470S. Ran it in 4WD for about 5-10 miles. That's with the Leer 180 topper and a Black Lab, maybe 300 extra pounds right there. Not bad at all. I'm pleased.

 

I have a stick, it drops gears when I say.

Better mpg at higher altitude is a fact. You discount lower air density and wind resistance as "tiny" but it's more like 20% less which is a lot. Driving 72 mph at 6000 ft has the same aerodynamic drag as driving 60 mph at sea level. Overcoming aerodynamic drag is what requires the most energy.

Planes fly at high altitude for a reason.

Ding ding ding ding..... my 1000th post.

 

There is not less oxygen in the mountains, there is less air pressure, but the amount of O2 is proportionately the same as at sea level.

 

I sleep at 5650 ft ...I know for a fact I'm more powerful at sea level when i travel to California I notice more boost so I would imagine I use more fuel but really haven't noticed hopefully someone here has hard facts

 

Readin is for fools in schools.

 

I'm confused now haha what did we decide?

I also didn't know you guys could get 85 octane... our lowest is 87, then we have 89 and 91, I have been thinking about going to 89 or 91 to get rid of the ethanol, I'll have to see how much is in each one...

 

Its most likely your lift/ tires and driving habits. I live at 7000 feet elevation and track my mileage on firmly and I'm averaging 19 MPG with basicly a stock truck

 

Proportionately isn't the concern, relative to sea level there is less oxygen in the mountains, which matters.

Tell someone at the peak of Mt. Everest that there isn't less oxygen there.

 

Actually, having been to Mt. Everest I had no trouble understanding I was short of breath because of less partial pressure, not less oxygen. I understand it affects the vehicle, but I enjoy the science of it all and wanted to bring it up. When I moved from sea level to 9,000' in 1993 I enjoyed increasing the timing on my old VW for this very reason... of decreased air pressure.

 

Cars get less MPG at higher altitude....PERIOD, no argument........I live between 9-12k feet everyday and my truck/every other car I've ever had does gets at least 3-4mpg less up here compared to the Front Range

 

Sorry but you can't just say no argument and make your statement true.

 

The density of the atmosphere is the key. You get more molecules per square liter at sea level vs. 10k.

 

He's not in the minority. JFGI. You should get slightly better mpg at altitude. Octane levels are lower here for a reason.

I get 19 mpg mixed city and highway with my V6 manual AC with 265/75/16 tires (duratracs). I drive a mountain pass at least once daily with an elevation change 2500'.

 

From the Internet:
"Effects of Air Pressure
Altitude decreases an engine’s octane requirements because of the change in air pressure. The higher elevations have a lower level of air pressure, which means an engine needs less octane to properly fire due to the lower ambient pressure. In certain states, such as Colorado where the altitude is generally above 5,000 feet in the mountain regions, 85 octane gasoline is sold, while in lower elevations 87 octane is the lowest sold.
End Result
When an engine requires lower levels of octane to “fire,” the overall efficiency of the engine is also lowered, which means the engine works harder to achieve the same results. However, less fuel burns, which means the overall fuel-per-mile efficiency is increased because the engine is working at a reduced compression rate. In short, you can get higher miles-per-gallon at higher elevations, but the power of the engine is also somewhat reduced."

 

UMMM, well I live here and have 2 cars that go back and forth between the 2 elevations and there is ALWAYS a difference.......Seeing how it works in everyday life doesn't LIE

and at least 1/2 of the people commenting don't even live any where near the elevation I do

 

soooo.....If this is true, someone please explain to me why I ALWAYS get worse mpg

 

If your engine power is suffering too much from the increased elevation then the car will need to run in a lower gear to generate enough power to get up an incline or hill. The lower gear/higher RPM's will drop your mileage.