Archives

I've been reading comments ( mostly included as an after-thought in post) that mileage will decrease during winter.

All engines operate most efficently after they reach a certain temperate. As outdoor temperatures drop, it will take longer for a car to reach optimal temperatues.

Next, for hybrids, the engine is usually required to reach a certain temperature before it will turn off. So again, it will burn more fuel. Additionally, when it does turn off, its temperature will drop off faster & it may have to run again just to maintain temperature.

Hybrids may use either heat from the engine (like tradtional engines) or electric heaters to heat the car. In the first case, you are again drawing off heat which may cause the engine to run. In the later case, you will use up battery power sooner & the engine will be forced to run for locomotion/recharge.

Colder air is denser, so additional energy is required to push a car throught it. As a plus, I believe the denser air alows a car to generate more power (like a poor mans turbo/supercharger), but I don't believe it does that without additional cost.

Snow/slush will create more drag than just water and will tend to remain a problem longer than water as it won't evaperate/sublimate as quickly as water will evaperate at higher temperatures. Also, it doesn't drain off as readily as water will.

In winter it is also darker for longer, when mean more use of headlights which drain hybrid battery or, in ICE only, may require alternator to run harder.

And lets not forget, with more darkness and poor weather, you also see more accidents/delays than summer which can further degrade drive (I'm speculating on this one).

Thats about all I can think of. But there may be others.

Now that the temperatures in IL are dropping to 40/60 degrees I'm already seeing my usual commute mileage drop from 40/44 down to 34/36. I'm sure that is going to get worse later in the winter.

Cold weather also increases the rolling resistance of the tires. The drag you down more, requiring more engine power. And rolling resistance is constant, whether you're going 5 mpg or 55 or 75.

Winter weather conditions can combine to lower fuel economy 20 percent, compared with the summer. In cold weather, a richer fuel-air mixture is required to start and warm up the engine. Also, much of the warmup may be done at idle (zero fuel economy) because of the need to defog or defrost windows. (During defogging/defrosting, many vehicles not only heat the air but use the air conditioner to dehumidify it.) More energy is required to overcome the resistance created by the higher viscosities of cold lubricants – engine oil, transmission fluid, and differential lubricant. Head winds increase air resistance; rain necessitates windshield wiper use; water or snow on the road increase tire-rolling resistance; and bad weather in general requires slowing to less fuel-efficient speeds. [Read more...] (http://www.chevron.com/products/PRODSERV/fuels/bulletin/fuel_economy/)

Note: The percent of decrease may vary, depending on the study.

Here (http://www.metrompg.com/posts/winter-mpg.htm) is another good list.

All of the above reasons, plus I'll add that certain hypermiling things that require conserving as much momentum as you can become unsafe in unpredictable road conditions, so there is more braking (and hence more ICE usage to get back up to speed).

I've got about 2 years of trip-level MPG data now (recorded with MPG-affecting factors such as temperature, road conditions, wind, and engine warm/cold), and as a ballpark I can expect to lose about 10% for every 25F drop or so, all other factors remaining equal. I'll post a few charts of temperature vs MPG for specific trips when I get home if I remember.

Nothing wrong with a little weight reduction, hateful! :)

Hi Cavalier owner (I dislike calling you Hateful :():

Accord in 70 – 90 degrees F in mid-summer: almost 59 mpg
Accord in -10 – 0 degrees F in mid-winter: almost 40 mpg.

___This is not a hybrid, non-hybrid issue although hybrids suffer more because their drivetrains do not allow some hybrid functions until coolant temps infer the CAT has lit off which happens much later nad maintaining coolant temp becomes a tougher proposition. Either way, there are multiple reasons for the hit as temps fall but you will feel the effect on a sliding scale no matter where you live once she drops below 70 degrees or thereabouts in just about anything.

___Good Luck

___Wayne

I know I'm feeling it! I'm already down ~5-8% from just last week on my normal commutes because the temperature dropped to 50F and under.

You do have an advantage that I've been seeing -- you're still improving as the weather gets colder so even as the cold undoes some of your work, you are still tightening up your efficiency habits. It has been getting cooler here for a while now but only now have I stopped increasing my numbers.

Keep working at it and remember that when Spring hits all your hard work will show you startling numbers as the conditions improve!

For people who are hybrid owners there is another major factor which I didn't see on any of these lists...batteries don't function as well at lower temperatures, so more energy is lost and the ICE runs longers.

And thanks for those lists. It was nice to see "top of my head" was pretty close, and to see the things I didn't know.

And ICE runs far richer... my LPH is 1.3 idling warmed up but cold it's over 4 - big difference in how rich the engine runs until up to temp and as it gets colder, the engine loses more and more BTUs to everything around it: under hood air, road spray, tranny, etc.

It takes a lot more BTUs to get the block heated with it starting colder and being able to lose heat to cold things all around it -- and all that extra heat boost comes from fuel enrichment.

1st - do you have an accurate reliable temp gauge ? I'd suggest getting one before performing a grille block . Most definitely consider the ScanGauge as it also has a temp gauge and will pull triple duty while saving you money on gas . fwiw I have 90% of my grille blocked and has been throughout my ownership.

ps...Welcome !!

The ScanGauge come highly recommended from, well, everyone. It's well worth the investment.

Let's not forget that many cities/States also mandate reformulated (boutique) gasoline in the Winter. Here in Reno we're on E10 year round but move to an E10 RFG from 10/1 to or through the Spring.

So far I've lost about 0.5 MPG from this year's RFG.

Boutique brings up a problem I have in Maryland. Sometime in the fall they bring in the "oxygenated" gasoline (reformulated gas - you can smell the difference). It supposedly decreases auto pollutants during the longer warm up time periods in colder temperatures. But it also decreases my MPG. It is a given, your MPG will decrease in the winter, because of all the excellent facts folks have mentioned. But you can do things to help yourself, like blocking some of the radiator (faster warmup), using block heaters (almost no warmup), making sure your engine oil is at the proper range for the temperatures you are experiencing, and clearing ice from your windows before you start the engine. I guess this is really crazy, but has anyone else noticed that if you shower in the morning, you fog up the windows worse???

If your hair is still wet that would explain it:D.