Definitely. Between longer time spent warming up and the "choke" effect of adding extra fuel when the engine is cold I've lost about 3 mpg.

 

Weird.
I drove 175 miles round trip to Mystic, Connecticut yeterday.
Zeroed the MPG before leaving.
90% Interstate 10% good, long secondary roads with few lights.
about 35-40° F

32.8 MPG on the DIC

 

Not so weird, one long trip is much more efficient then several short trips, especially in the cold. Everything is heated up and the parasitic drag Bill mentioned is much less of a factor... Besides, 35 - 40 really isn't that cold.

 

It's colder than summer and 31-33 is what I was getting on long highway roundtrips then.
I'm not a hypermiler per say but I set it at the speed limit in bad weather when I can.
I have been getting less MPGs but I have been doing more around town driving.

I'm not complaining anyways

 

I don't know about y'all, but man my little HHR has a lot more power when it is cold out. This is my first winter, and I can really feel a difference when the temps drop. It makes sense that the denser air charge needs an enriched fuel flow....both adding up to more power. Feels great. Costs more. Talk about cold air intake.

One observation....has anyone noticed your fuel economy on trips dropping when it is raining? On my road trips, I have noticed that my economy drops at least 2-3 mpg when in an average rain. I am attributing that to the tires pushing a small wave of water, or tire slip at some microscopic level. BTW, I have new all-weather Kumho tires on the car, so it is not a "Firestones" issue.

God Bless, Marc

 

I've dropped a couple MPG from what I was getting in September. I attribute the drop in mileage to the stations switching over to a winter blend of gasoline which causes lower mileage.

I know at one time it was true that in the NW there was a required by law switch in the fuel being sold during the winter. However, I haven't checked to see if that is still the case. I just hope it is and in the spring I expect my mileage to improve again.

 

I am down to 31.9 today as it has gotten colder.

 

wow ive been happy with 32 mpg now im looking foward to the spring lol

 

Part of the lost mileage may also be attributed to lower water temps. I have never really kept track of water temps and mileage but I think there is a relationship there. Probably more effecient at 200* than at 175*
Considering blocking off front grill to lower wind drag and help keep water temp up in Winter.
Some of the guys on the hypermiling web sites are doing that and claim it helps. Now your car will make more horse power (use more fuel to!) in cooler weather but not sure how that effects mileage. In fact some of them are using a WARM air intake and claim it helps mileage.

 

denser air= more fuel plain and simple. winter blends are pretty much myth nowdays. good friend of mine works as a "fuel blend auditor guy" (dont really know what the position is called) at the bp refinery here, he is there to verify the amount of ethanol in the fuel and other additives. he said all year the ethanol volume (in ohio its 10%) is kept the same and has been like that for quite a few years to stem rising fuel prices (high fuel prices actually hurt oil companies believe it or not) and according to him at least with bp the additives do not change through out the year. just my two cents.