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| winter gas mileage | |
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| Tweet Topic Started: Jan 29 2009, 09:14 PM (1,340 Views) | |
| Car Knocker | Jan 29 2009, 09:14 PM Post #1 |
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New Member
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Anyone hazard a guess why winter mpg is less than summer? I usually get 50 or better all summer in my 98 Metro,but now I'm lucky to be hitting 44-45 mpg. I know I warm it up a bit more now,and there is the ethanol additive in the winter gas , but can these two things knock down the mileage that much? |
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| Johnny Mullet | Jan 29 2009, 09:18 PM Post #2 |
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Fear the Mullet
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Yes they can. My 1998 Metro fuel mileage in now in the mid 40's compared to my average of 57 MPG. Cold weather, fuel mix, and the use of more electrical power (lights, heat, etc) all factor in. |
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| dimetrodon | Jan 30 2009, 12:06 AM Post #3 |
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Every lubricated component of your car that is not within the water jacket of your engine block gets stickier (technical term there...) as it gets colder. The wheel bearings, all the joints in the transaxle, all the oil inside the transmission, and probably also, to some degree, even your motor oil (exposed to the air-chilled oil pan) are cooler and therefore sap more horsepower from your engine as it tries to turn all the meshing gears, agitate the lubricants, rotate the bearings and move the car through the air. The result is you are pushing harder on the throttle, and burning more gasoline in the winter in order to achieve the same velocity. Of all the factors, the largest is probably the transmission since there are probably a lot of opportunities for the cooler, thicker oil to influence the efficiency of power transmission out to the drive shafts. |
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| metromad | Jan 30 2009, 02:00 PM Post #4 |
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Hmm, its a nice theory but one that I have always heard was incorrect. Not trying to be argumentative, but wind chill is a component of moisture being evaporated from a "damp" surface, i.e. skin. No moisture, no wind chill. Most mechanics I have talked to say that wind chill is not a factor in the winter. That is why you put your coolant anti-freeze level for the ambient air temp., not what wind chill would be. The cold oil problem is only present at startup and for the first few minutes thereafter. Once you have started the engine and begin moving, friction quickly overcomes any effects of cold. Even a greased wheel bearing begins to warm after a mile or so. Well, that is my take on it. Personally, I think most of the fuel usage is because of the enriched fuel cycle at start up. Also, when the temp is 32 or below, I notice my car cooling off fairly quickly so you figure if you make a few stops during the day, you are probably getting into the enriched fuel sequence several times, thus dropping your mileage. The best way to reduce the fuel used, at least on initial start, is to invest in a block or oil pan heater. This will get you out of or at least reduce the time spent in the first and coldest fuel enrichment cycle of the day!
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| jeff | Jan 30 2009, 02:52 PM Post #5 |
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Or.......(read this somewhere) Today's motor(gas) are engineered from OEMs to run hotter. Hotter is more fuel efficient. So with that reasoning & our 10degree temps + windchill......there goes the mpg a bit. |
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| Will | Jan 30 2009, 10:25 PM Post #6 |
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Victory is mine!!!!
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Colder air is also more dense. This causes more aerodynamic drag on the car. It is not enough to really notice on the average car, but when you are driving a 50+ mpg car it does not take much to hurt your mpg. I personally am now getting about 10 mpg less than I was in the summer. I think the time it takes to warm the car up is also a factor. I notice that my Metro is "stiffer" when it's cold. The shifter does not want to move, and the car seems to have lost power vs. summer driving. There are a few level places in my commute. During the summer I cruise these at about 55 mph pulling 14-15 inches of vacuum. Right now to do the same thing I am pulling only about 12 inches of vacuum. |
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| Bad Bent | Jan 30 2009, 11:48 PM Post #7 |
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Facetious Educated Donkey
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Metrompg.com lists 9 reasons for lower gas mileage and his records for his gas mileage dropping 28%. 1. More idling Even in the coldest weather, you can begin driving after 30 seconds from a cold start - keep speeds low/moderate and use gentle acceleration until the temperature gauge starts to climb (source). 2. Low tire pressure A 10-degree (F) change in ambient temperature equates to a 1 psi change in tire pressure (source). Fuel economy declines 0.4 percent for every 1 psi drop (source). 3. Increased rolling resistance Rolling resistance at 0 degrees F is 20% greater than at 80 degrees (source 1, source 2). 4. Crappy road conditions It's increased rolling resistance of another kind: driving through slush and snow. And then there's its wasteful polar (no pun intended) opposite: no friction at all! (A.K.A. wheelspin on ice.) 5. Lower average engine temperature In the winter, an engine takes longer to reach operating temperature and cools off faster when shut off. Since the engine management system orders up a richer mixture when cold (proportionately more fuel in the air/fuel combination), more fuel is being burned overall. A block heater can offset this problem (improving fuel economy by 10% in sub-zero conditions - source), as can garage parking, and combining trips (to minimize the number of cold/hot cycles). Also related... 6. Higher average lubricant viscosity Engine oil thickens as it cools. So does transmission and differential fluids and even bearing grease. 7. Weaker gasoline Gasoline doesn't vaporize readily at very cold temperatures. So oil companies formulate fuel differently for cold-weather markets in the winter. Unfortunately, the changes that provide better cold vaporization characteristics also result in less available energy for combustion. You won't get as far on a liter of winter gas as you will on a liter of summer gas. (Source.) 8. Higher electrical loads lights (in higher lattitudes it's darker in the winter), rear window defroster (easier thanthe ice scraper, right?), heater blower motor, windshield washer pump (easier than the ice scraper, right? And road spray.) 9. More aerodynamic drag A vehicle�s aerodynamic drag is proportional to air density, and the density increases as temperature drops. For every 10 degree F drop in temperature, aerodynamic drag increases by 2% (source). Edited for space. Just FYI. |
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| New2metros | Feb 1 2009, 08:24 AM Post #8 |
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Member
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My mpg is really been in the crapper lately. But it average below zero for the last month. But I got a remote start that really been taking it down also. When it was warm I getting about 38 with it but lately been 26. The automatic has to go soon so I can get better mpgs. |
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| Hacksaw | Feb 2 2009, 01:37 PM Post #9 |
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Disciple of Johnny Mullet
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Latest MPG for me was 33.9...Not anything to brag about to be sure... |
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