So I've noticed that my MPG has gone down....significantly. About 3 or 4 weeks ago I've started to noticed that I'm down about 20miles or so less on a full tank of gas. Could this be b/c of the cold weather? I've checked my tire pressure and my driving has not become any more aggressive than the previous months. My Airfilter is damn clean as well.

EDIT: I use to get 300 +/- miles on one take not I get about 280 +/- miles on one tank....

 

^ its the winter gas. It will get better when spring comes Trust me yours isnt that bad, mine is crazy bad in the winter. not bad in the summer...but gas prices are back where they should be so no worries!

 

I remember in another thread somewhere lobux was explaining why you get better mileage in the summer and warm weather than cold. You only want cold air when going WOT but warm in just daily driving. Something about running more effeciently that way.

 

Hmmm, weird. Just wanted to make sure it wasn't just me.

 

that is new... my mpg hasn't gone down yet.. it's still at 22-23.5

 

A lot of this could be driving habits, too. Not just yours, but other people as well. When it gets cold / slippery, people tend to drive at more variable speeds (e.g slowing down more at intersections even thought the light is green, etc.) and this can drastically effect your mileage.

I find my mileage is about 10% worse now than it was in September.

 

speaking as a mechanical engineer: the law of thermodynamics says efficiency increases as workable engine temperatures increase...

for instance an engine working at 800 F is about 30% efficient vs. a engine working at 3500 F is about 85% efficient. this is just an example no exact numbers...

then you ask: why aren't engines designed to run at higher temperatures. well its simple, current oils, lubes, and metals cannot withstand the high temps. this is why your experiencing lower efficiency numbers.

also the winter gasoline is probably not much help.

 

This is true, the computer works to keep the engine warm in the winter or operatng temp tus using more fuel on top of the different emission blend.

 

right around 1 october each year i notice a 10% hit.

i also saw in a couple of places it is because of the "winter" gas.

the warmer climates may not change gas, maybe that is why some dont notice.

 

My MPG fell to 15.5 from 19.5

 

check @your pump. In the northwest we get a 10% ethanol mix in the winter. ethanol = less btu's = less mpg. Go search out mpg for e85 vs. gas, there's a dramatic difference.

 

From 27-29mpg to only 24-25mpg

 

i haven't paid any attention yet but with premium being 1.80+ and regular going for 1.50+, I sorta don't mind anymore xD (for the moment)