I've had 2 Sentras (91 SE traded w/158k, 97 GXE still driving w/183k) and both have acted the same. I've learned to expect it, but still am curious. Can anyone explain, please?
I drive 120 highway miles/day commuting. Every fall when cold weather comes to Iowa, my gas mileage drops about 10%. From 38mpg to about 35. When spring comes it goes back up. If I go south for a winter vacation, the mileage goes up, then drops off when I return home. Both cars have done this since they were new. Is this the cars response to the cold air? Is it a result of winter formula gas? BTW I use 10% ethanol, unless I can't find it. Thanks. P.S. I don't idle the car to warm it up during cold weather.
Steve
southiowa
Last edited by saharv23 : Mar 16th, 2003 at 05:46 AM.
saharv23: you said you're located in south iowa, where exactly are you? i live in Muscatine, Iowa, on the mississippi river, on the east side of the state...
We just got back from a trip to the Gulf coast and gas prices were cheapest in Mississippi. Lowest I saw was 1.49. Mostly 1.60 to 1.69. But of course, prices are dropping now that war is eminent. Gofigger!!
We just got back from a trip to the Gulf coast and gas prices were cheapest in Mississippi. Lowest I saw was 1.49. Mostly 1.60 to 1.69. But of course, prices are dropping now that war is eminent. Gofigger!!
Stay on topic, folks. Reformulated winter gas can indeed cause lower fuel mileage. More oxygenates are used in winter and they have poor heat value, so they don't contribute much to energy available in a gallon of gas. Alcohol is an oxygenate. Typically, reformulated gas is used in large metro areas that have air quality problems. You rural guys should never see it.
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Bruce in Houston
'94 Nissan Sentra SE-R w/ $tuff, converting to ITA
'98 Suzuki Bandit 1200S w/ $tuff
'02 Dodge Dakota SLT 4-dr tow beast, stock!
Well, the answer is the following. All cars do this. The reason is two-fold:
First, the denser colder air requires more fuel to keep the air-fuel ratio as required by the engine controller. Second, those of you that have studied thermodynamics may know that engines that work at higher temperatures are more efficient. That is part of the reason Diesels are more efficient (and also the reason why you will rarely--if ever-- find an aluminum block Diesel. ) The fact that the engine is working in a cold harsh climate will lower its efficiency, therefore requiring more fuel to do the same amount of work.
So, regardless of the effect of the gas, changes in ambient temperatures alone will make a difference such as changes in altitude will make a difference because of changes in air density.
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