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Discussion Starter · #1 ·
Ambient temperature and MPG; extent of the connection? POLL

Dear All
Touareg owners have seen the discussions re MPG and will know whether they are personally above or below the posted averages, given their type of driving, rural or urban.
I'd like to explore if there is an inverse relationship between MPG and ambient temperature; i.e. if I drive in a cold climate (sub-zero) will I get a substantially worse MPG regardless of driving conditions and urban vs. rural etc.
Y'all know if you are currently in a cold/temperate/warm climate
I am in a cold climate with my V6 and consider my overall 12.2 below average; given reports of up to 13/14 as a possible average, and 15 or higher as above average. I'm curious as to why, given that I am NOT heavy footed/aggressive in driving style. At least, i don't think so.
Perhaps someone would post equivalent values/ranges for V8 ??
C'MON NOW, MAKE YOUR OPINION/EXPERIENCE COUNT!



Modified by mmmmm127 at 8:04 PM 2-13-2004
 

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Re: Ambient temperature and MPG; any connection? (mmmmm127)

Without specific numbers, I don't know what constitutes good / bad mileage or cold /moderate / warm climate.
I live in Richmond, VA which has an average annual temperature of 57.7 degrees (F). In my V8 Touareg, I get an average of 14.7 MPG on the highway and 11 in the city.
-J
 

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Re: Ambient temperature and MPG; any connection? (mmmmm127)

A poll will not answer your question. Cold temperatures will reduce your gas mileage for various reasons. Here is a list from various sites on the intenet.
Reason 1 - Gasoline, like any other liquid, evaporates less when it is cold. You have seen this -- if you pour water onto a hot sidewalk it will evaporate a lot faster than it will from a cooler place like a shady sidewalk. When it gets really cold, gasoline evaporates slowly so it is harder to burn it (the gasoline must be vaporized to burn). Sometimes you will see people spray ether into their engines in cold weather to help them start -- ether evaporates better than gasoline in cold weather.
Reason 2 - Oil gets a lot thicker in cold weather. You probably know that cold pancake syrup or honey from the refrigerator is a lot thicker than hot syrup or honey. Oil does the same thing. So when you try to start a cold engine, the engine has to push around the cold, gooey oil and that makes it harder for the engine to spin. In really cold places people must use synthetic motor oils because these oils stay liquid in cold temperatures.
Several things conspire to lower your mileage in cold weather. One is lower tire pressure. Even without any leaks, tire pressure drops about a pound for every 10-degree drop in temperature. So if you haven't checked the pressure since it was 80 degrees in the shade last summer, you may have lost enough tire pressure to seriously reduce your mileage.
These types of tips are all over the internet with a quick search.
 

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Discussion Starter · #4 ·
Re: Ambient temperature and MPG; any connection? (jsewell)

Thinking more of current temperature and current MPG; but yes, it is a bit subjective.
 

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Discussion Starter · #5 ·
Re: Ambient temperature and MPG; any connection? (spockcat)

Quote, originally posted by spockcat »
A poll will not answer your question.

OK, if you don't want to play, that's fine
EDITED--->No but to be serious; yes obviously cold climate equates to poorer MPG; that's a given, and for all the obvious reasons but I'd be interested to know if this were NOT happening with the Touareg, i.e. if people reported the counterintuitive result.
I am assuming my poor MPG is because of cold climate driving and I'd be interested to see that indeed was the case, or not. Clearly such a poll requires a large denominator, but that may not be happening it seems



Modified by mmmmm127 at 7:31 PM 2-13-2004
 

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Re: Ambient temperature and MPG; any connection? (spockcat)

Quote, originally posted by spockcat »
Sometimes you will see people spray ether into their engines in cold weather to help them start -- ether evaporates better than gasoline in cold weather.

In reality, ether should not help in the above process since ether already permeates all space in the universe.
 

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Re: Ambient temperature and MPG; extent of the connection? POLL (mmmmm127)

The primary reason for poor mpg in cold weather is due to the engine being cold - not due to the ambient air temperature being cold. If your car were parked in a heated garage (72F) you would probably see an improvemnt in mpg at cold ambient temperatures. Cold air is heavier which means you get more oxygen to burn each cycle which should improve the mpg. However, if your engine is cold, not only is the oil thicker, but the clearances between the piston and cylinder are larger which reduces the power produced by the engine. As it says in the Touareg manual the engine should not be driven hard until the oil temperature has risen above 140 F.
If you take a long trip in cold weather (4 hours or more) does your mpg get better? I thimk it would.
 

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Re: Ambient temperature and MPG; any connection? (****us)

Quote, originally posted by ****us »
In reality, ether should not help in the above process since ether already permeates all space in the universe.

This was a cut and paste directly from the Car Talk website. If they spelled something incorrectly or misused a word, it's not my fault.
 

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Re: Ambient temperature and MPG; extent of the connection? POLL (mmmmm127)

An old trick we used to use to get the engine to warm up more quickly in sub-zero weather is to place a piece of cardboard in front of the radiator to stop the air flow through the radiator. I'm not suggesting that you do this for the Touareg, just remembering 30 year old experiences on the farm.
 

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Re: Ambient temperature and MPG; extent of the connection? POLL (PassatBill)

I've done that too, but I think this method mostly helps with older vehicles since their fan was directly driven from the engine, on the new ones it turns on/off depending on the coolant temperature. Also that's why you have a thermostat - to run the fluid through the short path while engine is cold and through the radiator when it heats up.
 

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Re: Ambient temperature and MPG; extent of the connection? POLL (PassatBill)

Actually, if the thermostat is working correctly, this should be required on any engine. If the engine doesn't have a thermostat or it isn't working correctly, then this would help it warm up.
Broken thermostat is another thing that causes poor fuel mileage in cold weather.
 

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You really have to hide off topic stuff these days, but for those with a few moments to pass, go look at the ebay advert for a jag 420, and the obvious fun the seller is having with the would be purchasers' enquiries:
jaguar advert
 

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Re: (mmmm127)

Another thing to consider: I know in Colorado, and probably in other states, too, the fuel in the wintertime is "oxygenated" to help reduce air pollution which can be worse in the winter months because of temperature inversions wherein warm upper air traps colder surface air and the pollutants do not disperse. Oxygenation of the fuel helps reduce not only pollution but GAS MILEAGE! I can trace almost exactly when the station I use for gas switches over to oxy winter fuels, as I can count on the mileage in any of my cars dropping about 1 mpg or so. You may want to investigate whether fuels in your area are oxygenated.
 

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Re: Ambient temperature and MPG; any connection? (jsewell)

Quote, originally posted by jsewell »
I don't know what constitutes good / bad mileage or cold /moderate / warm climate.

-J

Yes, the questions are a bit difficult. I should have offered gas mileage sucks, freezing outside/ gas mileage sucks, warm outside/ gas mileage great, freezing outside, gas mileage great, warm outside.
Horses for courses....
 
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