My experience: Gas mileage as a function of temperature

[BobJustBob]

About a week after I got the so-called customer satisfaction update (13B07, the one that supposedly will increase our gas mileage) this past August, I started keeping a spreadsheet tracking the per-trip gas mileage I experience while driving to work in the morning.  I record this as a function of temperature.  I have a very short commute--8.6 miles--and a good fraction of it is downhill.  I do not keep track of my commute home because I frequently run errands during my evening commute, while I almost never do during my morning commute.

 

I am posting my results here.  As many others have noted, temperature is a really big factor in gas mileage for the C-Max.  My one-year anniversary of C-Max ownership is coming up in one week (November 21st).  My current lifetime gas mileage is 39.9 mpg.  I so want to get that final one-tenth mpg in order to be able to say I am averaging 40 mpg.  But it is tough--I live in a very hilly area, and one with cold winters.

[bigalpha]

Temperature of what?

[BobJustBob]

Ambient air temperature.

[fotomoto]

Back in 2009, I went to a grass roots style test drive of pre-production Volts in San Antonio.   They had some engineer types there and when I asked one about battery temps vs performance he said, "if your comfortable, it's comfortable" and added that 70-80's was best which jives with your spreadsheet pretty well don't you think?  Folks that drive in a temperate climate (SoCal for example), typically get much better mpg's than everyone else.  I've seen it proven on forums over and over again.

 

When I was shooting for a 900 mile tank, my final run was on a near perfect day:  74f, low humidity, and no wind.  I achieved over 72mpg for the entire day not just one trip.    

Edited November 16, 2013 by fotomoto

[bigalpha]

How many fill-ups do you have?

[BobJustBob]

Sixteen.

[salsaguy]

16 is not enough data points to be a representative sample. need 30-50 data points. more is always better even analyzing data.

but yes most folks know temp is a big contributor for good mpg.

i also track my mpg for both in and back from work and track the outside temp, if ac or heater was used, travel time, avg speed on mph, if i had traffic or no traffic, etc, so i know which data points are valid to use and part of the same "process"and which to throw out.

 

if you have a copy of Minitab statistical software you can do some good data analysis and control charts to know which data are/aren't valid.

[viajero]

16 is not enough data points to be a representative sample. need 30-50 data points.

 

Looks like he has a lot more than 16 data points.  I think the OP is graphing the dash computer results for each day, not for each fill up.

[fbov]

In my mileage analysis, I've found I need to track both temperature and weather, as wet and dry roads are similar, but if it's raining, snowing or there's standing water, results shift. I see signs of two different performance populations in your data, perhaps there's something different in your morning commute some days? It could be as simple as starting SOC, especially with a downhill run.

 

Or, you could be learning to drive more efficiently... this car's been teaching me quite a bit! And not all of it about driving....

 

HAve fun,

Frnak

[fotomoto]

In my mileage analysis, I've found I need to track both temperature and weather, as wet and dry roads are similar, but if it's raining, snowing or there's standing water, results shift.

 

Yeah for me it's the unseen:  wind AKA our gulf breeze.   Typically, mornings are calm and afternoons are strong.   

[hybridbear]

About a week after I got the so-called customer satisfaction update (13B07, the one that supposedly will increase our gas mileage) this past August, I started keeping a spreadsheet tracking the per-trip gas mileage I experience while driving to work in the morning.  I record this as a function of temperature.  I have a very short commute--8.6 miles--and a good fraction of it is downhill.  I do not keep track of my commute home because I frequently run errands during my evening commute, while I almost never do during my morning commute.

 

I am posting my results here.  As many others have noted, temperature is a really big factor in gas mileage for the C-Max.  My one-year anniversary of C-Max ownership is coming up in one week (November 21st).  My current lifetime gas mileage is 39.9 mpg.  I so want to get that final one-tenth mpg in order to be able to say I am averaging 40 mpg.  But it is tough--I live in a very hilly area, and one with cold winters.

Have you plotted a regression equation for this data? What's the r²? I'm currently working on something similar for our FFH, but since I walk to work I don't have a repeatable commute. I'm currently gathering data on all trips and then plan to segment the data to create some graphs and find patterns.

 

Great data! Very insightful!

[fbov]

Excel does curve fits through the trendline option on scatterplot charts. I include the equation and R^2 when I post data from my car.

 

Just keep in mind that a low R^2 means one of two things:

- the data's noisy

- the pattern is flat

 

Most folks understand noisy data, but the second is as common. If the car's mileage doesn't vary with temperature, R^2 will be zero, regardless how tightly grouped the data.

 

HAve fun,

Frank

[ptjones]

About a week after I got the so-called customer satisfaction update (13B07, the one that supposedly will increase our gas mileage) this past August, I started keeping a spreadsheet tracking the per-trip gas mileage I experience while driving to work in the morning.  I record this as a function of temperature.  I have a very short commute--8.6 miles--and a good fraction of it is downhill.  I do not keep track of my commute home because I frequently run errands during my evening commute, while I almost never do during my morning commute.

 

I am posting my results here.  As many others have noted, temperature is a really big factor in gas mileage for the C-Max.  My one-year anniversary of C-Max ownership is coming up in one week (November 21st).  My current lifetime gas mileage is 39.9 mpg.  I so want to get that final one-tenth mpg in order to be able to say I am averaging 40 mpg.  But it is tough--I live in a very hilly area, and one with cold winters.

The graph I did showed 2MPG per 10degree drop in temperature.

 

Paul

[dlapean]

Well,......I'm not graphing anything,......but being from Wisconsin, I can state that the cooler temps have resulted in my C-Max dropping 3 tenths off of it's average.  I was averaging 40.7 during the summer and even the fall,......but recently it's gotten into the 30's for daytime temps and my average has dropped,....now at 40.4.

Also wondering,.........does using the heated seats have any effect on electricity draw, as far as gas mileage, I suspect NOT, but I will say that those seats at just a setting of '2',......get very hot and draw a lot of electricity.  Can't image anybody using heated seats at a setting of '5',........scorched buns.

[fotomoto]

Also wondering,.........does using the heated seats have any effect on electricity draw, as far as gas mileage, I suspect NOT, but I will say that those seats at just a setting of '2',......get very hot and draw a lot of electricity. 

 

An easy way to see the difference in power drawn is to call up the usage meter in "My View".  

 

Anything that draws on the battery is a potential mpg killer but the wattage on the seat heaters (on lower settings) is probably small enough that other variables in a daily drive obscures it.