Your mileage in the winter will always drop. The cold air needs more fuel and therefore lowers your mileage.

What if you went to the gas station filled your car up until the pump clicks then slowly drove it to a parking space and let it idle for 15 or 30 minutes then slowly drove back and fill your tank again until it clicks. Whatever amount of fuel it takes to fill it the second time will be very close to the amount of fuel it take for however long you let it idle.

Josh,

 

wouldnt it be warmer and more gas friendly to just sleep in your bed for a half hour longer and get to work when its time to go inside?? lol

 

Yeah, I guess it would. But here's the deal. I get up at 4:30 and then drive about and hour and fifteen minutes to work. I get there between 6:20 and 6:30. Even though we have a flexible work schedule, we don't get credit for starting before 7:00. If I were to leave much later than I do in the morning, it would probably take at least two hours to get to work. Plus I'm one of those people that HATES getting up early so if I'm able to take a little nap before going into work, I'm good. Yeah, I know, I'm odd. :-)

 

Just bring some blankets... it's cheaper... easier on the engine... and are comfy as hell.

 

It's on the order of 1/2 gallon per hour, with a margin of error of 1/8th gallon.

About 7 yrs ago I was interested in the same thing, so I topped it off, idled for 2 hours, and then was able to put just under 1gal in it.

Also if it didn't affect your mileage last winter it probably isn't affecting it this winter. There's no doubt you're using gas idling but not any more than last winter.

There's too many variables in gas mileage to pinpoint one problem. It could be the gas itself. Not every gallon of gas contains the same amount of energy. It could be formulated differently for environmental regs or it could contain more ethanol (just a few years ago only the crappy gas stations had ethanol, which has less energy per gallon than gasoline, blended with their gas but now in Atlanta you won't find any gas station that doesn't have those little disclaimer that says "may contain up to 10% ethanol"). Maybe your tires are low on air. Maybe your average trip length is shorter this winter because you moved closer to work or make more short trips. Maybe you take different roads now with more stops. Maybe you drive differenlty. Maybe you're fatter.

 

lol
if you get 34mpg I wouldn't be complaining

 

Interesting that this thread popped back up. We've had some mild days here recently and I was able to turn the engine off when I got to work for a couple of days. I have to conclude that it was simply the idling that wrecked my mileage. I got almost 38 mpg the last time I filled up. Maybe last winter I just "thought" I got about the same mileage.

 

Civic 2004, Exi 1500 cc.

1.4 liter per hour without AC, 1.8 with AC.