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I have an EX with CVT and mileage has dropped from about 425 miles per thank to just under 300. All variables are the same and I can't figure why I'd see a 30% drop. Any guidance would be helpful.
 

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colder temperature? :dunno:
 

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9 Reasons Why Your Winter Fuel Economy Bites!

As if we really needed another reason to hate winter.

Those of us living in northern climes have already started to notice the seasonal decline in fuel economy, even with careful attention to sagging tire pressure (probably the best known effect of the mercury's slide).

Yet, despite diligent all-around maintenance and continued careful driving, cold weather fuel consumption can be dramatically worse than in warm temperatures.

How much worse?

Have a gander at these calculations for a Honda Civic hybrid at 60 MPH in varying ambient temperatures:

MPH-----AMBIENT-TEMP-----MPG (US)

60------------95----------52.98
60------------85----------52.62
60------------75----------51.16
60------------65----------49.12
60------------55----------47.22
60------------45----------44.67
60------------35----------43.05
60------------25----------41.54
60------------15----------39.41
60------------05----------38.09

Look at the extremes: the coldest MPG is 28% lower than the warmest. (Source.)

My own experience supports this: 12.5% worse mileage during the colder half of the year (Oct 15 to Apr 15) than for the warmest half (Apr 15 - Oct 15), on average 2002-2004 in my 1989 Accord. Comparing just the warmest months (Jun-Aug) to the coldest (Dec-Feb), the difference is even more apparent - 21.2% worse (2002).

Why so bad? Off the top of my head, I could think of a couple of reasons to explain it, but together they didn't seem significant enough to account for the magnitude of the change. With this mystery to solve, I hit Google. And here's what I learned...

9 reasons your winter fuel economy bites

1. More idling

This should be a no-brainer, yet parked idling cars are a common sight in cold weather. Resist the temptation to idle your car to warm it up. An idling engine gets 0 mpg. Consider also that idling the engine does nothing to warm up the tires and drivetrain.

Even in the coldest weather, you can begin driving after 30 seconds from a cold start - keep speeds low/moderate and use gentle acceleration until the temperature gauge starts to climb (source).

2. Low tire pressure

Of course you're smart enough to keep up your tire pressure as the temperature drops, right? A 10-degree (F) change in ambient temperature equates to a 1 psi change in tire pressure (source). Fuel economy declines 0.4 percent for every 1 psi drop (source).

3. Increased rolling resistance

Even if you're completely attentive to proper tire pressure, cold ambient temperatures will still cause your tires to return worse mileage. That's because a tire's shape isn't completely round - the sidewall bulges out at the bottom, and where the tread meets the road the small contact patch is actually flat. As the tire rotates, it constantly deforms to this shape, and this deformation requires more energy when the rubber is cold and hard. Rolling resistance at 0 degrees F is 20% greater than at 80 degrees (source 1, source 2).

4. Crappy road conditions

It's increased rolling resistance of another kind: driving through slush and snow. And then there's its wasteful polar (no pun intended) opposite: no friction at all! (A.K.A. wheelspin on ice.)

5. Lower average engine temperature

In the winter, an engine takes longer to reach operating temperature and cools off faster when shut off. Since the engine management system orders up a richer mixture when cold (proportionately more fuel in the air/fuel combination), more fuel is being burned overall.

A block heater can offset this problem (improving fuel economy by 10% in sub-zero conditions - source), as can garage parking, and combining trips (to minimize the number of cold/hot cycles).

Also related...

6. Higher average lubricant viscosity

Engine oil thickens as it cools. So does transmission and differential fluids and even bearing grease. Significantly more energy is needed to overcome the added drag these cold lubricants cause.

Using synthetic fluids can address this problem, since their viscosity changes less at extreme temperatures than traditional mineral fluids.

7. Weaker gasoline

Gasoline doesn't vaporize readily at very cold temperatures. So oil companies formulate fuel differently for cold-weather markets in the winter. Unfortunately, the changes that provide better cold vaporization characteristics also result in less available energy for combustion. You won't get as far on a liter of winter gas as you will on a liter of summer gas. (Source.)

8. Higher electrical loads

In colder temps, you use electrical accessories more often:

- lights (in higher lattitudes it's darker in the winter)
- rear window defroster (because it's easier than using the ice scraper, right?)
- heater blower motor (I don't have a/c, so this isn't balanced out during warm conditions); heated seats/mirrors
- windshield washer pump (because it's easier than using the ice scraper, right? And for frequently cleaning off dirty road spray.)

9. More aerodynamic drag

No, I'm not referring to the layer of snow you're too lazy to brush off the top of the car (though that would hurt mpg too).

A vehicle’s aerodynamic drag is proportional to air density, and the density increases as temperature drops. For every 10 degree F drop in temperature, aerodynamic drag increases by 2% (source).

http://www.metrompg.com/posts/winter-mpg.htm
 

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^^ This guy knows how to Google for sure! :yes:
 

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2020 Honda Accord Sport 2.0T 10AT
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9 Reasons Why Your Winter Fuel Economy Bites!

An idling engine gets 0 mpg.
Only one disagreement.

An idling engine gets negative miles per gallon.

When you're at a stoplight (the longer the better) watch your gas mileage drop as the seconds go by.

An engine that is not running gets 0 mpg.
 

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Only one disagreement.

An idling engine gets negative miles per gallon.

When you're at a stoplight (the longer the better) watch your gas mileage drop as the seconds go by.

An engine that is not running gets 0 mpg.
Idling engine gets 0mpg.
Your mpg is dropping because a 0 score hurts your average score.

Negative mpg is rocket science.
 

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It seems that the miles left in the tank is calculated on the latest average mpg that's showing on your display. If you get on the highway for a trip and raise that up, your miles will go up accordingly (no pun intended).
 

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2014 V6 EXL Sedan
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I revisited your BIBLE for reasons and it is probably the idling that is hurting my FE. You will see me cross the finish line with vigor as victor when my new CVT Honda will get 35 CITY MPG in my 100% CITY driving. I will be yelling "C'mon..." as I see you in my rearview non-dimming mirror at you murmuring marty marty marty
Wasn't my bible by the way, wasn't my post! I just thought it had a lot of plausible reasons and was impressed with the depth.

Actually you probably won't see me in your rearview mirror at all since I will be long past you with the raw acceleration of my v6. Unless we are in a looooong race of 400 plus miles, in which I concede I will need to stop for gas more quickly than you will :) But if you do catch me in your non dimming rearview you'll clearly know it is me due to my awesome LED DRLS :)
 

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Luv2Drum
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I'm attributing this little dip in my MPG to the winter gas. Though it was the first tank of Texaco, I had been using Chevron since I bought the car.
 

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I have an EX with CVT and mileage has dropped from about 425 miles per thank to just under 300. All variables are the same and I can't figure why I'd see a 30% drop. Any guidance would be helpful.
Well...if all variables are truly the same you're no doubt simply hallucinating. More likely you're just a troll.
 

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Does the 6AT with the VCM and DI really get sub 6 0-60 numbers. If so, wonder why that does not get more pub. Sub 6 numbers were the holy grail of this class so I am surprised this does not get more media if indeed it is true.
I was surprised to see sub6 seconds 0-60 on the Accord V6.
But Camry V6 also does 0-60 in 5.8 or something.
I guess it's not that special nowadays..

Both Accord and Camry V6 are fast,
but 0-60 and quarter miles are not the only factors that determine the car's overall performance.

BRZ/FR-S has been getting rave reviews when it came out.
It does 0-60 in 7.xx seconds.
 

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2014 V6 EXL Sedan
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Does the 6AT with the VCM and DI really get sub 6 0-60 numbers. If so, wonder why that does not get more pub. Sub 6 numbers were the holy grail of this class so I am surprised this does not get more media if indeed it is true.
As my car is new with 550 miles on it, I haven't totally floored the accel and redlined the car yet with a stopwatch and measured myself. I've heard stats that say it is around 5.7 or 5.8 secs. All I know is the car is fast in acceleration and has lots of power and torque, and is much smoother than the CVT. I drove the CVT too. It is nice, just not as smooth and powerful.
 

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Does the 6AT with the VCM and DI really get sub 6 0-60 numbers. If so, wonder why that does not get more pub. Sub 6 numbers were the holy grail of this class so I am surprised this does not get more media if indeed it is true.
I don’t believe the V6 has direct injection. It still uses multiport but still makes the Accord fast. As far as publicity goes, there are many V6 family cars today that are 6.0 seconds to 60 or less - Camry, Accord, Passat , Altima, Maxima, Mazda6, Charger, Impala, Legacy Turbo just to name a few. With today’s new technology it is expected.
 

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I have an EX with CVT and mileage has dropped from about 425 miles per thank to just under 300. All variables are the same and I can't figure why I'd see a 30% drop. Any guidance would be helpful.
Don't overlook the significance of tire pressure (#2 on the list). When the temps dropped from the 60's to the 30's in a matter of days, my mileage dropped from ~32 to ~28. I blamed it on the cold, and the winter gas, but a week later i noticed my tire pressure was in the high-20's on all 4 tires (usually low-mid 30's).

I brought the pressures back to normal levels, and my mileage has improved to ~30 now.

Every little bit helps...
 

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I think winter mix gas plays its role as well as prolonged warm-up time.
 
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