Winter not good for mileage...

[14Corolla]

I'm noticing I can't get the mileage in the cold that I was working on during summer.

First.... My car idles faster in the cold. Not just a choke. It keeps the idle up after warming up.
As a result of this. Hypermilling by coasting is not working. I'm doing better by just coasting in drive. Maybe tap a little to keep speed up. That is better for mileage than coasting with the idle up and coasting slowly down slower.

The above is by far the biggest reason. There are others for winter in general. I know gasoline might be different. Also we tend to let the car idle in the cold. Other reasons...

I do have these new tires on the car. I did good mileage. Not the best on first tank. It has cooled off since. Am resorting my game plan now. I love these tires. Handle great. Ride great. Great in wet. Haven't seen ice yet. I've even thought to forget about an anti sway bar for the back. Back end does much better with these tires.

Will continue to experiment with premium/regular mix. Right now, 20% premium seems to be doing about the best.

Anyways... I'm still working with high 30's on mileage during winter so far. I do notice just how touchy mileage is with just the slightest change in gas pedal and rpm. I must really be pushing it to get the mileage I've been getting. I've lost my 40 something mileage till spring.

[SteveMak]

A big reason for reduced fuel economy in cold weather is that things stiffen up and thereby create more resistance. Think in terms of belts, less springy suspension, bearings that resist rotation (they're everywhere!), a transmission and differential and universal joints that resist movement. These things are not suddenly negated when your car's water temp or oil temp come up to the normal operating zone, either.

Late in 2015, I drove from Ontario Canada to Florida. My car has a real-time fuel consumption meter (liters per 100 km, with 1 decimal place). Yes, I know, it's not accurate, but it will give you a relative reading, so I know my summer averages, and I will definitely notice a change. The trip started with diesel fuel bought in Canada with temps around 50'F. Level driving was indicating about 4.5 L/100 km @ 80 kph (50 mph). We made our way into the West Virginia mountains by the end of day 1, an altitude of about 2500 ft ASL. We woke up the next day with freezing temperature (below 32'F). The car was "cold soaked." After driving over an hour, with a thoroughly warmed-up engine but still in freezing ambient temps, still with Ontario fuel, we were showing over 5.0 L/100... going downhill, and over 6.0 on level roads!

After refuelling in Virginia (getting perhaps "winter fuel"?), we were still showing high fuel consumption readings in the cold weather. As the weather got warmer the further south we drove, our fuel consumption also got lower (better). By the time we got to Georgia with temps around 70'F, we were showing our normal indicated 4.5 L/100 km or so.

I believe this experiment debunked the "winter fuel" belief for me, because I saw the same fuel deliver relatively poor fuel economy in freezing weather, and normal (good) economy in warm weather. Cold temperature has an effect for the duration of the trip.

I also acknowledge the reduced fuel economy during the engine warm-up process. This is exacerbated in freezing weather. But this effect only effects your fuel economy at the start of the trip, until your engine is thoroughly warmed up.

[trollbait]

With the introduction of common rail diesels, fuel stations no longer sell a winter blend diesel, which contains some kerosene. Instead, they sell winterized diesel that contains additives that prevent any wax that comes out of solution from clumping into flakes and clogging stuff. Winter blend will have a lower energy density than straight diesel due to the added kerosene. The additives for winterized diesel likely aren't enough to dilute out the diesels energy density.
https://en.wikipedia.org/wiki/Winter_diesel_fuel

Winter gasoline energy content, on the other hand, is still diluted out by the addition of less energy dense fuels like butane.

The extra idling past the engine reaching temp is likely due to the ECM warming up the catalytic converter. A grill block can be fashioned cheaply, I've used cardboard, and helps with warm up and aero. An air dam to reduce airflow underneath might help in keeping the cat warm.

[Charon]

Automatic transmissions may not upshift into the higher or highest gear until the engine warms up, and they may also inhibit torque converter clutch lockup. In cold weather, of course, it takes longer for the engine to warm so the transmission stays in lower gears longer. That probably affects overall fuel mileage.

[SteveMak]

Originally Posted by Charon

Automatic transmissions may not upshift into the higher or highest gear until the engine warms up, and they may also inhibit torque converter clutch lockup. In cold weather, of course, it takes longer for the engine to warm so the transmission stays in lower gears longer. That probably affects overall fuel mileage.

Just as a data point, in my example a few posts up, my driving was virtually all highway, for many hours, in top gear. The exception was 5-10 minutes driving to get onto the highway. Your statement does not apply to my example, though it still might have some detrimental effect on fuel economy.

[R.I.D.E.]

Yesterday we took a day trip. Temps in the low 40s, that reached 70 in the afternoon. I had topped the tank off the day before the trip so I included that top off with the refill when we got home. Total miles driven was 366, of which 246 were the trip itself.

I aired the tires up to 50 psi, colder weather had dropped them from 45 to 40 psi over the last 6 weeks or so after the last top off. Most of the trip was on 55 mph secondary roads with the last 50 miles on Interstate at 100 kph (62mph).

Working fairly hard on the secondary roads, I managed to get the mpg reading on the factory instrumentation to 58.8 mpg. The ultra gauge was slightly lower at 57.8. The last leg was 50 miles of Interstate, 295 beltway around Richmond and 64 east to Williamsburg and home.

On the Interstate the traffic was heavy, so I slipped in behind a big rig going almost exactly 62 mph (100kph). To my amazement the mpg reading actually rose over the last 50 miles to home, even with the 100kph average speeds. No hypermiling tactics were employed, just steady driving 3 stripes (128 feet) behind the truck. Most of the other traffic had separation distances much less than that, in some cases less than one car length (20feet).

When I got home the factory gauge was reading 60 mpg, while the ultra gauge was reading 58.4. I stopped at the same station, same pump and refilled the car eactly the same as before.

59mpg.

Not really winter driving, but I am fairly sure we are on winter blend fuel now.

To those who wish to not believe that mileage, my fuel logs are available as evidence.

E10 cheap WAWA gas.

[14Corolla]

Interesting to read other's experiences. I appreciate it.

For me. When I talk about higher idling. I'm talking about after warming up. My car normally, in warm weather, idles at 700rpm. In the cold, it idles at 1300. I even noticed, when it wasn't that cold, low 40's. When I stopped at a stop sign. Put it in neutral. It idled at 1000. Leaving that stop sign. Driving at 50mph. Put it in neutral to coast. It held 1300.
I can put it back in drive. At the right speed. It will bring down the idle from 1300. This is a CVT. Or CV transmission. I do really like it. Convinced this is a major part of my ability to get 40 plus mpg in summer conditions.
Basically.... this ruins my hypermilling practice of coasting in neutral.
It ruins my high mileage.
On Friday it snowed. Slippery, icy out. Drove at 25 to 30mph. Talk about mileage taking a death dive.
Oh well... The car is real nice. Very comfortable. Love these new tires. They do great in winter road conditions.
There are other wintery reasons. Appreciate people talking about them.

[litesong]

Originally Posted by Charon

Automatic transmissions.....In cold weather.....so the transmission stays in lower gears longer.

Unless ya got an Elantra. Mine shifts into 6th gear at 43mph.... summer or winter.

[trollbait]

Originally Posted by 14Corolla

Interesting to read other's experiences. I appreciate it.

For me. When I talk about higher idling. I'm talking about after warming up. My car normally, in warm weather, idles at 700rpm. In the cold, it idles at 1300. I even noticed, when it wasn't that cold, low 40's. When I stopped at a stop sign. Put it in neutral. It idled at 1000. Leaving that stop sign. Driving at 50mph. Put it in neutral to coast. It held 1300.
I can put it back in drive. At the right speed. It will bring down the idle from 1300. This is a CVT. Or CV transmission. I do really like it. Convinced this is a major part of my ability to get 40 plus mpg in summer conditions.
Basically.... this ruins my hypermilling practice of coasting in neutral.
It ruins my high mileage.
On Friday it snowed. Slippery, icy out. Drove at 25 to 30mph. Talk about mileage taking a death dive.
Oh well... The car is real nice. Very comfortable. Love these new tires. They do great in winter road conditions.
There are other wintery reasons. Appreciate people talking about them.

Do you have a Scangauge or other way to monitor the transmission temperature?

[gonzobob]

I think another big reason is colder, lower humidity air provides more resistance. At least I know it always seems a lot harder to ride bicycle in the cold and I'm always going a bit slower.