Check out the hardcore posters in the database.
That would be anyone who entered data over most of the year.

Click on the name of their car.
First you will see a graph of their MPG vs. Month.

You will notice mileage is best during the warm summer months.
Then people from certain states will get a MPG hit during the months requiring air conditioning.

Why does cold weather lower mileage?

Good Question !!! Here are a couple of reasons:

1. Battery - The cold "saps" the battery's ability to hold it's charge - the charge trickles away faster. So more of your gasoline is used for recharging the battery. So although ALL vehicles suffer MPG problems in cold weather, we Hybrid owners suffer even more... :angry:

2. Fuel reaction to the cold - The fuel does not vaporize as well in the cold, and the computer will run the engine richer until it is warm, using more fuel.

3. Shorter days means more headlight use, and the additional load on the alternator uses more fuel.

4. Engines are more efficient after warming up - and if your trips are fairly short, you will suffer MORE because the engine will never reach full efficiency before the end of the trip.

5. Cold Tires - Rubber gets stiff in the cold, so tires from overnight parking take longer to warm up and until they do, they have higher rolling resistance, which also contributes to additional fuel usage.

more later....

I would also add fuel or gasoline formulation.

Diesel #2 is mixed with diesel #1 (Kerosene) to a certain amount.

The more #1 you get the less fuel economy.

Less BTU's per volume.

I guess it's the same for gasoline. :(

So that's why there's a 14 mpg difference in between February and August. :blink: :(

There are mods you can do to recuperate part of mileage lost because of weather... ;)

I thought NiMH batteries LIKE cold? They'll hold more charge when cold.



For the Hondas, the main difference is the cold engine. Owners have discovered that if they cover the radiators with cardboard, and trap the heat, they'll get summer-like MPGs.

Here is the scoop on NiMH and cold:
So yes, they lose deliverable capacity in cold weather....

What owners? How can you trap the radiator heat and keep the engine warm enough on a cold night to get "summer-like MPGs?

Look at the Real Mileage Database and find me an owner who got "summer-like MPGs" in winter in a cold environment...that I'd pay to see..... :D

Even if you DO trap the engine heat, you have only addressed ONE of the many issues which affect Hybrid MPG in cold weather (see my above post).....

Hi All:

___The following might help: Warm Air Intake vs. Warm Engine Temp.

___A radiator block mod will not come close to Summer temperature driving FE in temps below ~ 60 degrees. A radiator block and warm air intake mod will not do it either but each adds their own component to improve FE in colder and colder external ambient temperatures. 2 more components are needed to solve the problem once and for all imho.

Stupid Puddles!

___About half way down the page of the linked thread, the discussion for the final solution comes into play. A totally sealed bay, warm fuel, warm air for the intake, and warm coolant all together in one nice package. Wheel bearing temps and such cannot be cured but they are not a huge drag imho. All of this talk about battery pack temps and such lowering FE is getting close to bunk for the Honda IMA setups in particular. Since the Prius I and II are forced to use the pack for some amount of propulsion, only a small portion of this discussion makes sense for them as well given the packs are ~ up to internal ambient in a matter of 5 minutes or so.

___Good Luck

___Wayne R. Gerdes
___Hunt Club Farms Landscaping Ltd.
___Waynegerdes@earthlink.net

Owners at insightcental or honda-hybrid. The cardboard blocks the air & prevents it from cooling the engine while driving. That enables longer lean-burn.



I'm aware of the other issues but "For the Hondas, the ***MAIN*** difference is the cold engine."

When it's really cold here (mid-thirties for you snow-birds) the dash temp guage reaches about half (Normal) in about 1.5 miles or about 2-3 minutes.
MPG has improved but the drive train has not warmed up yet.

I usually drive for about 10 miles...or about 15 minutes before I consider it warmed up enough to move the cabin temp off of cold :ph34r:

I'm not sure if I'll try any mods at all this winter given Atlanta's climate.

Another reason that cold weather lowers mileage is that cold air is more dense (thicker) than warm air, so your car is literally having to shove aside a greater weight of air as it travels down the road when it is cold, which results in increased aerodynamic drag. If you drive the same route the year round and do a lot of freewheeling as you drive, this temperature effect on aerodynamic drag is very noticable and can result in as much as a 15mph reduction in your terminal velocity at the bottom of the hill when you crest the top at about 60mph between a 90F summer day versis a 0F winter day. There are many moderate downgrades on which I can maintain speed when freewheeling in the summer where I slowly drop speed when freewheeling in the winter. Also in the eastern US, the relative humidity (RH) is typically lower in the winter than the summer. Humid air is less dense than dry air, so the dry winter air takes a hit on your mileage.