Notices

Is it possible?

I would like very much to monitor my fuel efficiency at any given moment, and see rolling averages (over 10 minutes and over each tank).

Thanks,
Matt

I wholeheartedly second this request.

This feature has been requested here

There is already an application in Extras (or Extras-Devel) which supports this, but not automagically, nor does it have OBD2 support.

This is in our roadmap but it is not an easy task. From the OBD2 perspective, the standard does not provide the fuel consumption information directly. You have to get it from the mass of air/fuel that goes into the engine. If anyone can help with that, please do it. We can build a simple python program to do that so that everyone can test it.

What is the name of this new application?

Fuelpad.

Garage project page.
ItT thread.

It is in Extras-Devel; not Extras.

Theres also Mileage.

You can't get fuel economy from OBD2. The Mass Air Flow (like RPM) is a snapshot of the current value, and you would need to integrate the value over time. For the time of the snapshot it would be accurate, but the update is around 6hz if you don't look at anything else. (On my Harley, the J1850 bus is 16Hz for RPM and speed, and has an incrementing fuel consumption bus message, and one for odometery so with a bit of computation and time stamping I can get instantaneous fuel economy).

Maybe its better to use GPS for this?

But I have seen plotting done with Carman (using GPS + OBD2). It was showing how fast (in different colours) the driver was driving on the road.

Say, some trips are tax deductable. Or you want to know your monthly fuel expenses. Or effectiveness of litre:km. You could then use some kind of automation process to count.

While something like Fuelpad is nice, everything has to be filled in manually.

Fuel economy is affected by too many things, so if you aren't just recording how many gallons at each fill up v.s. odo reading (I use my trip odo for this and write the reading on the receipt) you can't just go on speed or distance, or acceleration for that matter. The RPM might show gear, but is fairly intermittent so you might not catch the actual shift points.

Minigpsd kml plots have their height proportional to the speed (and I wrote a colorizer as a post-processor). I've been trying to backfill some of my journeys of the past few months to calculate my MPG, but I do have live fuel and distance in my vehicle's datastream, along with RPM and current gear. But that varies for each vehicle.

I am interested in real time fuel efficiency so that I can directly see how my driving habits influence my fuel consumption. I always measure my fuel efficiency from tank to tank; but that process is too slow to give me the feedback I need to finely tune my habits.