I was discussing MPG of my Subaru with my father, a retired math professor, and he made a good point regarding MPG calculation. When fueling, especially when using the automatic shutoff feature on most pumps, the amount of fuel put in varies significantly. Therefore, if I just drove 250 miles and put in 10 gallons of gas, I might think my MPG was 25, not realizing this particular pump shutoff a half gallon sooner than the one from last fill up, causing an inflation of my actual MPG. If one is more interested in accurate Spot or Trip MPGs, one would have to put in a measured amount of fuel each time. Having a full tank is more important to me than this as the flucuations wash out for Lifetime MPG, of course.
Fisker Mileage Calculator
There's been a lot of talk about what kind of real-world mileage we'll experience with our Karmas. I decided that when I get my car I'm going to carefully track how much fuel I'm putting in, and how far I go.
I looked around for a logbook to keep in the car to jot down each fill-up but I couldn't find one I liked. Instead, I fired up Excel, leveraged some ideas and templates from the Internet, stayed up past my bedtime and created a Fuel Calculator for my Karma.
I'd like to invite you to be a beta tester and provide feedback. You can download my work-in-progress from the link below.
A few notes about the tool:
Update: The link below will now always point to the latest version. Read later entries in this thread to learn about the improvements I've made.
Click Here to Download the Latest Version
All feedback welcome. Feel free to send me a PM through the forum.
Thanks!
Brent
I looked around for a logbook to keep in the car to jot down each fill-up but I couldn't find one I liked. Instead, I fired up Excel, leveraged some ideas and templates from the Internet, stayed up past my bedtime and created a Fuel Calculator for my Karma.
I'd like to invite you to be a beta tester and provide feedback. You can download my work-in-progress from the link below.
A few notes about the tool:
- There are four tabs: the Mileage Calculator, the Mileage Chart, a Printable Log and a printable Service History
- The Mileage Calculator is where all of the magic happens. You put in the Date of each fill-up, along with the current odometer reading, and the amount and cost of the fuel. Excel calculates the rest
- The tool calculates Spot MPG (what you observed since the last Fill-up) and Lifetime MPG
- The Mileage Chart helps you visualize the data and identify trends
- The Printable Log is intended to be kept in the car and used to write down Fill-up details.
- The Service Log is likewise intended to be printed and kept in the car. I use this for all of my vehicles to record all service perfomed, tire changes, warranty work, etc
- I've populated the tool with some sample data. It's all made up but hopefully plausible
- I'm running Excel 2007. No guarantees it'll work for you or on another version
- Once this is polished I'll make it available to any and all who wish to use it
Update: The link below will now always point to the latest version. Read later entries in this thread to learn about the improvements I've made.
Click Here to Download the Latest Version
All feedback welcome. Feel free to send me a PM through the forum.
Thanks!
Brent
1 - 14 of 14 Posts
Yes. The variation drops a lot if you use the same pump at the same station all the time (not always easy to do), or you can "top off" the tank by hand (not always wisekabalah70 said:I was discussing MPG of my Subaru with my father, a retired math professor, and he made a good point regarding MPG calculation. When fueling, especially when using the automatic shutoff feature on most pumps, the amount of fuel put in varies significantly. ...
) but it's best just to use a longer term average.Looks good, and works fine on Excel 2010. When I did my test drive (waaaay back in August) I asked the Fisker Rep if there was going to be some sort of online tracking for owners to input their data (along with their issues), as I thought it could be a tremendous sales tool for Fisker. He said they were considering something at the time, but I never heard anymore about it. This will work great for me, that is, IF I ever have an actual car.
Thanks Guys!
I've already got a v2 in the works with some improvements. I'll post it soon.
I agree about the variability of auto-shutoff, which is why the spreadsheet runs primarily off of the metered amount of fuel pumped. Yes, each pump will have a different definition of "full", and the sheet only calculates Spot MPG correctly if you fill up, but I think the error discrepancy will be trivial. For my purposes, it'll be good enough to say "I'm getting about 85mpg" or hopefully "I'm getting about 185mpg"
Keep the feedback coming!
Brent
I've already got a v2 in the works with some improvements. I'll post it soon.
I agree about the variability of auto-shutoff, which is why the spreadsheet runs primarily off of the metered amount of fuel pumped. Yes, each pump will have a different definition of "full", and the sheet only calculates Spot MPG correctly if you fill up, but I think the error discrepancy will be trivial. For my purposes, it'll be good enough to say "I'm getting about 85mpg" or hopefully "I'm getting about 185mpg"
Keep the feedback coming!
Brent
I have an easier solution, although maybe slightly less robust.
The Karma comes with two trip calculators, A and B. Each one tells you how many miles you have traveled and the combined gas mileage you have experienced. For my "A" trip computer, I never re-set it, so when I look at that one, it is telling me my overall experience since purchase. I reset the "B" one each time I plug it in, so that I get the mileage for my most recent electrical "fill-up". I would say that I could also use B every time I fill it up with gas, but so far, the car still has most of the gas it was delivered to me with. 500 miles so far and only a gallon or so of gas use.
The B computer, when I am in all stealth mode for any given 50 mile segment, always tell me I am getting above 400 MPG (people love to see that on my command center screen), but it won't give you a reading to infinity ;-). My combined one since purchase (Trip "A") is telling me I have experienced 290 MPG. One test would be to start with an empty battery and let my B computer calculate what MPG I would get over 100 miles or so, and see how it compares to the EPA all-gas calcs. But to do that, I'd have to burn gas for the test, which I don't want to do until I go on a long trip somewhere.
The Karma comes with two trip calculators, A and B. Each one tells you how many miles you have traveled and the combined gas mileage you have experienced. For my "A" trip computer, I never re-set it, so when I look at that one, it is telling me my overall experience since purchase. I reset the "B" one each time I plug it in, so that I get the mileage for my most recent electrical "fill-up". I would say that I could also use B every time I fill it up with gas, but so far, the car still has most of the gas it was delivered to me with. 500 miles so far and only a gallon or so of gas use.
The B computer, when I am in all stealth mode for any given 50 mile segment, always tell me I am getting above 400 MPG (people love to see that on my command center screen), but it won't give you a reading to infinity ;-). My combined one since purchase (Trip "A") is telling me I have experienced 290 MPG. One test would be to start with an empty battery and let my B computer calculate what MPG I would get over 100 miles or so, and see how it compares to the EPA all-gas calcs. But to do that, I'd have to burn gas for the test, which I don't want to do until I go on a long trip somewhere.
Fisker Mileage Calculator version 2
Ok, I've made some tweaks. Click here for version 2:
Fisker Mileage Calculator v.2
Release notes:
Again, all feedback welcome!
Brent
Ok, I've made some tweaks. Click here for version 2:
Fisker Mileage Calculator v.2
Release notes:
- Replaced Cost-per-mile with Cost-per-gallon. Cost-per-Mile was pretty meaningless since it doesn't account for electricity cost. There are lots of tools out there that estimate or track that, but that's out of scope for what I'm looking to do here. I put in Cost-per-gallon just because it'll be interesting to be able to track what happens with fuel prices.
- Resequenced the columns on the Mileage Calculator sheet, placing the four that require data entry together. Also changed the shading to indicate which fields are manually entered and which are calculated
- Updated the Printable Log to only include the four columns of data you need to capture at each fill-up
- Added a Version History tab, with an enhancement idea scratchpad
Again, all feedback welcome!
Brent
My current car does not even have A-and-B. I just keep a log book in the car and record mileage and quantity (and price and date and so on) at each fill-up. In most cases I use the trip odometer to measure miles between fill-ups.Dave_Car_Guy said:I have an easier solution, although maybe slightly less robust.
The Karma comes with two trip calculators, A and B. Each one tells you how many miles you have traveled and the combined gas mileage you have experienced. For my "A" trip computer, I never re-set it, so when I look at that one, it is telling me my overall experience since purchase. I reset the "B" one each time I plug it in, so that I get the mileage for my most recent electrical "fill-up". I would say that I could also use B every time I fill it up with gas, but so far, the car still has most of the gas it was delivered to me with. 500 miles so far and only a gallon or so of gas use.
The B computer, when I am in all stealth mode for any given 50 mile segment, always tell me I am getting above 400 MPG (people love to see that on my command center screen), but it won't give you a reading to infinity ;-). My combined one since purchase (Trip "A") is telling me I have experienced 290 MPG. One test would be to start with an empty battery and let my B computer calculate what MPG I would get over 100 miles or so, and see how it compares to the EPA all-gas calcs. But to do that, I'd have to burn gas for the test, which I don't want to do until I go on a long trip somewhere.
Since the Karma has an actual computer instead of just a limited set of hardwired counters, it really should let you select a "start new trip named <fill in the blank>" at any time, and count up from current odometer reading (or store it as an odometer offset that is subtracted from "current reading" for display purposes until that trip is marked "ended", but that's an efficiency tweak that will only matter if there is a large number of active trips*). The trips page should show you all the current active trips (and let you mark any of them "ended", which stops them counting up), show ended trips (maybe let you "resume" them too), and let you delete or reset them.
That page should probably come with basic "trip A" and "trip B" pre-loaded, but that should not be a limit, just a starting point.
[hr]
* I.e., instead of:
Code:
for trip in active_trips:
trip.distance += 1 # one tick = 1/10th mile or 1/10th km or whatever
Code:
odometer.reading += 1
Code:
for trip in active_trips:
trip.distance = odometer.reading - trip.offset
for trip in sorted(active_trips + stored_trips):
trip.display()Fisker Mileage Calculator version 4
I've owned my car for a couple weeks now and have moved in to my spreadsheet. It's working well for me as a way of keeping track of my actual consumption, and also as a consolidated tool to track issues as I encounter them. I've made some tweaks. Click here for version 4:
Fisker Mileage Calculator v.4
Release notes:
The Squawks sheet uses conditional formatting on the "Date Observed" cell as follows:
Again, all feedback welcome!
Brent
I've owned my car for a couple weeks now and have moved in to my spreadsheet. It's working well for me as a way of keeping track of my actual consumption, and also as a consolidated tool to track issues as I encounter them. I've made some tweaks. Click here for version 4:
Fisker Mileage Calculator v.4
Release notes:
- Added Squawks worksheet to record observed issues and their status
- Protected sheets and cells from inadventant change (no password)
- Changed odometer precision to whole miles to match odometer in vehicle
The Squawks sheet uses conditional formatting on the "Date Observed" cell as follows:
- Yellow background color indicates a new occurrence that hasn't yet been reported to my dealer
- White/no background color means an active, open issue that the dealer is aware of
- Green background color indicates a resolved issue
Again, all feedback welcome!
Brent
What sort of fuel economy have you been getting (e.g. in pure Sport mode)?LonePalmBJ said:I've owned my car for a couple weeks now and have moved in to my spreadsheet. It's working well for me as a way of keeping track of my actual consumption, and also as a consolidated tool to track issues as I encounter them. I've made some tweaks. Click here for version 4:
Fisker Mileage Calculator v.4
Release notes:
- Added Squawks worksheet to record observed issues and their status
- Protected sheets and cells from inadventant change (no password)
- Changed odometer precision to whole miles to match odometer in vehicle
The Squawks sheet uses conditional formatting on the "Date Observed" cell as follows:
- Yellow background color indicates a new occurrence that hasn't yet been reported to my dealer
- White/no background color means an active, open issue that the dealer is aware of
- Green background color indicates a resolved issue
Again, all feedback welcome!
Brent
In "mixed mode" around town involving some stealth, some sport and some nighttime charging I got 53.8 by the time of my first fill-up, which included a lot of goofing around with Sport mode and 100+ mile daysSoCalGuy said:What sort of fuel economy have you been getting (e.g. in pure Sport mode)?
I also took an 1100 mile roadtrip last week, virtually all in sport with a depleted battery. Here are the tank-to-tank MPG calculations for the trip. On the highest mpg segment the battery had some charge on it before I set out but I don't think was full: 23.9, 20.4, 29.9, 20.2, 21.0, 22.5
This was all "worst case scenario" driving for the Karma: Constant 80mph on the highway, with minimal braking or regen, and the occasional burst of throttle to pass someone.
Of course, since my roadtrip I've driven the Karma about 200 miles all stealth and haven't been in sport or range-extend mode once, so infinite MPG. That's what makes the "so, what kinda mileage do you get" question so complicated!
Brent
LOVE IT! I've found my peeps - car loving spreadsheet types! The only suggestion would be to include a version# in the file name, so we can keep up with your latest and greatest.LonePalmBJ said:There's been a lot of talk about what kind of real-world mileage we'll experience with our Karmas. I decided that when I get my car I'm going to carefully track how much fuel I'm putting in, and how far I go.
I looked around for a logbook to keep in the car to jot down each fill-up but I couldn't find one I liked. Instead, I fired up Excel, leveraged some ideas and templates from the Internet, stayed up past my bedtime and created a Fuel Calculator for my Karma.
I'd like to invite you to be a beta tester and provide feedback. You can download my work-in-progress from the link below.
A few notes about the tool:
- There are four tabs: the Mileage Calculator, the Mileage Chart, a Printable Log and a printable Service History
- The Mileage Calculator is where all of the magic happens. You put in the Date of each fill-up, along with the current odometer reading, and the amount and cost of the fuel. Excel calculates the rest
- The tool calculates Spot MPG (what you observed since the last Fill-up) and Lifetime MPG
- The Mileage Chart helps you visualize the data and identify trends
- The Printable Log is intended to be kept in the car and used to write down Fill-up details.
- The Service Log is likewise intended to be printed and kept in the car. I use this for all of my vehicles to record all service perfomed, tire changes, warranty work, etc
- I've populated the tool with some sample data. It's all made up but hopefully plausible
- I'm running Excel 2007. No guarantees it'll work for you or on another version
- Once this is polished I'll make it available to any and all who wish to use it
Click Here to Download
All feedback welcome. Feel free to send me a PM through the forum.
Thanks!
Brent
Rex, Thanks! Be sure to download v.4 from my latest post. You can tell the version on the Version History tab.
I'll also update the Original Post with a link to the latest.
I'll also update the Original Post with a link to the latest.
Very Useful! I just downloaded your lovely spreadsheet onto my phone (aka mobile computer) to eliminate the need to transfer data to the spreadsheet from handwritten notes. Now as I wait for the pump to pump I will open up this spreadsheet, enter the data and glory in my lack of gas useage. I intend for that to be an infrequent occurance. Thanks LonePalm!
1 - 14 of 14 Posts
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