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Discussion Starter · #1 ·
I'm looking for help in understanding Karma dashboard information on gasoline and electricity consumption that allows estimation of fuel economy.

Our goal is to design a Web-based form to help owners track Karma fuel economy data over time and, optionally, to share that information with the public on FuelEconomy.gov (http://www.fueleconomy.gov/).

Thanks!...Rick
 

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What do you need to know, Rick?

The Karma runs for up to 50 miles (~42-48 miles under typical driving conditions) without using any gasoline, so if one's regular use of the car is < 50 miles between charges, then it gets 857349857298357298347398734 (infinite) mpg since it uses no gas at all.

If run purely on gas, it gets something like 20-28 mpg. But really, no one buys the car to run it on gas, so the only gas-heavy use of the car would be for long trips.

In my case I've driven the car about 1500 miles and never even opened the fuel door yet, and I still have about 3/5 of a tank of gas left, so I'm getting > 350 mpg over the lifetime of the car. And I don't think this is unusual.

It's great to not have to drive to a gas station and fill up every 10 days like I used to.
 

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goeltz said:
I'm looking for help in understanding Karma dashboard information on gasoline and electricity consumption that allows estimation of fuel economy.

Our goal is to design a Web-based form to help owners track Karma fuel economy data over time and, optionally, to share that information with the public on FuelEconomy.gov (http://www.fueleconomy.gov/).

Thanks!...Rick
If you're asking specifically about which metrics are provided to the user it's sadly pretty sparse.

The vehicle supports two trip counters, Trip A and Trip B, and will display miles driven and MPG for each... and that's about it.

On the gasoline side, there's no lifetime MPG, Lifetime Fuel Consumption, Trip Computer fuel consumption (although you could calculate this), or current-drive fuel consumption. There is no instantaneous MPG readout either. One particular quirk is that the MPG reading maxxes out at an arbitrary 409MPG. Even if you never use gasoline the car will report 409MPG. There are plenty of "409 = Infinity" comments scattered across this forum.

On the electric side it's even more scant: There's pretty much no information about electricity use apart from an instantaneous KW-being-used-or-generated readout. There's no available metric of total kWh used, miles per kWh, no charging details such as most recent or lifetime or current charge time or consumption, battery life or capacity. There's no information on total lifetime or Trip energy created via brake regen/hill mode and no information whatsoever on energy created by the solar panel.

I expect that many of these metrics are actually tracked by the vehicle, but none of them are available to the user via the dashboard or Command Center. I don't know what, if any, metrics are available via the OBD connector.

For my own use I created a tracking spreadsheet that provides some better fuel economy tracking. You're welcome to leverage it for any ideas. You can read more about it here and Click Here to Download the Latest Version

Brent
 

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With about 8875 miles on my car and only 21 gallons of gas so far I'm at around 422 MPG without factoring in electrical use.
But then I run almost exclusively in stealth mode.

In regards to the dash the gauges are just a rough estimate. I have also found the the trip computer calculations do not seem to jive with the manual calculations either....but I had issues early on where my spedo stopped recording mileage for some 1800 miles.
 

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Discussion Starter · #5 ·
Brent:

That's exactly what we needed to know. Unfortunately, it is bad news that we cannot track the electricity consumption.

Your spreadsheet looks good. We have an online version called Your MPG; see https://www.fueleconomy.gov/mpg. We are working on adding data input forms for EV and PHEV. Note that Your MPG computes a 'harmonic mean' which I understand is appropriate for the average of 'rates'.

Thank you very much for the info...Rick
 

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A harmonic mean, as stated in Wikipedia, will "mitigate the influence of large outliers and increase the influence of small values".

It would appear that a harmonic mean would yield values that skew pessimistic. Do you have any insight as to why harmonic mean was chosen to be used instead of median? Median values mitigate the influence of outliers on both ends, and would seem more accurate to me.
 

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What we really need is to be able to access realtime data as well as data stored by the computers. I have been tempted to get a Bluetooth OBDII sensor, but the standard software that works with those only collect and display data from the ICE, and would not be able to collect or display data from EV operation, as I understand it.

It would be nice if there was an EV or Fisker specific App that would work with an ODBII sensor that we could use to get better insight into the car's performance.
 

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I use Brent's excellent spreadsheet on my iPad. I added two columns to calculate the percent of time on gas vs electric miles, by plugging in the 26mpg hwy - which I confirmed as a typical figure for HWY driving - i use stealth in town, and have only used gas (sport mode) when taking a long trip, involving hwy driving.

By taking the gallons used, and multiplying by 26, I get "gas miles driven"... Which I subtract from total miles driven to get electric miles.

I'd be happy to share the data. With almost 3000 miles, including a few long trips, I am a north of 100 mpg. [hr]
I just tried the govt form. Pretty nice. Though, I had to laugh when it kicked out an error at my gas mileage was too high (too many miles between fill-ups, was the warning message). Yea. That is kind of the point of the car -- to use hardly any oil.

Fisker owners... If you have you gas receipts and mileage readings, add your records.

The EPA figures are totally off base from my driving experience. The EPA says 21 mpg hwy. I systematically measured hwy mpg at a range of set speeds from 55-80 over 113 miles in roughly 3 mile increments with an average of 65 mph, and got 26mpg. So the epa's 21 is not reflective of how the karma is used. On city streets, or when traffic slows to a crawl, that's when a karma owner uses all electric. Next, epa says electric range of 33 miles! The 33 mile range is also not consistent with my experience. I am in the 40s.

Goeltz, In terms of the form, It would be nice to reset the tolerance for a fisker, and to back into the electric vs gas miles used. I hope you get owner participation. More data is good!
 
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