MPG for LE 4WD
- Thread starter Neauxla
- Start date
Bilbo
New member
Here's an interesting controlled study about altitude and fuel economy. Essentially, they found that higher altitude was associated with better fuel economy under stop-and-go driving conditions. However, higher altitude was associated with reduced fuel economy under highway conditions.
They quantified fuel consumption by measured CO2 emissions. The comparison altitudes were sea level (229') and 7,200'. Higher altitudes showed 3.5% and 2.6% better fuel economy under their two city-type driving models. Under the highway model, there was a 6.2% increase in fuel consumption.
http://www.wseas.us/e-library/conferences/2009/vouliagmeni/EELA/EELA-29.pdf?origin=publication_detail
Another big factor is the gas. I used to live in a place that had very little ethanol in the gas. When I moved to Austin, where you can't find gas without 10% ethanol, my MPG dropped 2mpg in my 2003.
Now, I have a 2014 LE 4x4 and it started off around 14mpg when it was new. I have almost 2,000 mile on it now and it's improved to about 17mpg in the city.
A recent trip got me about 20 to 21 mpg.
All stock (so far...)
Now, I have a 2014 LE 4x4 and it started off around 14mpg when it was new. I have almost 2,000 mile on it now and it's improved to about 17mpg in the city.
A recent trip got me about 20 to 21 mpg.
All stock (so far...)
1engineer
Moderator
I did a thread awhile back looking at this from a theoretical point and a seat of the pants look lol. Here it is http://www.toyota-4runner.org/5th-gen-t4rs/133786-cold-air-horsepower.html
03_4x4Runner
Senior Member
I see you are in Louisiana. It is flat there I believe. 20s would be possible there, move to the mountains out west and it is a whole new ballgame.
Bilbo
New member
From "not an engineer" here: You have altitude --> horsepower (all other things being equal). Is there also a direct relationship between horsepower and fuel consumption? Or does extracted energy per unit of fuel vary by altitude? Or something else entirely?
Thanks!
JayceeP
New member
Since Aug 2013 (over 12,000 miles) my overall average is 16.8 mpg. In the warmer months, I'm consistently getting17-18mpg in day-to-day suburban driving with some hills and some traffic lights. A small portion is city driving. In the winter this drops to around 15.5-16.5 mpg with tanks in the low 14mpg range when it got really cold. My commute is about 5 miles each way.
On the highway, anything above 18mpg is good for me at 75mph and very uncommon. 17.5 is probably more normal... But keep in mind my highway trips are rather hilly and can be windy windy. Best I have achieved is when I drove down to DC last Aug (before I started keeping track) and my computer got around 21mpg doing 75-80 the whole way down I95 including Boston and DC traffic. I95 is very flat.
On the highway, anything above 18mpg is good for me at 75mph and very uncommon. 17.5 is probably more normal... But keep in mind my highway trips are rather hilly and can be windy windy. Best I have achieved is when I drove down to DC last Aug (before I started keeping track) and my computer got around 21mpg doing 75-80 the whole way down I95 including Boston and DC traffic. I95 is very flat.
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1engineer
Moderator
A gallon of gasoline has a certain amount of potential energy and that is measured in BTU's. It has that same potential at any altitude.
The next part is kind of tricky but basically the higher you go the less air (oxygen esp) you have to work with. As we know oxygen is important in burning! Also remember that we burn a vapor of fuel, not the liquid itself. So the less air, the less explosion, the less oxygen in the vapor and *poof* the less combustion which equals less horsepower. That's technically not 100% correct but it tells a better story that way and its close enough. Turbochargers and superchargers are nice to have at altitude since forced induction will make up for some of that loss. You can also burn lower octane fuel at altitude without fear of knocking or pinging. Basically its the air, not the gas part of the horsepower equation.
Bilbo
New member
[MENTION=66316]1engineer[/MENTION] So when Zervas ("Impact of altitude on the fuel consumption of a gasoline passenger car") used CO2 emissions as a measure of fuel consumption, he may have failed to account for uncombusted fuel? That's amusing.
Modern cars use feedback to do a very good job of putting out as little uncombusted fuel as they can, even at altitude. The catalytic converter takes care of the rest, so if there is uncombusted fuel it will turn into more CO2 there.
I typically get better mileage in the mountains than elsewhere, but I think that's mainly because the speed limit in the mountains is low 55-65, and because climbing hills (higher engine load) and coasting down (no fuel used if in gear) is a bit more efficient than driving the same distance at a constant, low engine load.
