Is idling factored into fuel consumption reading?

[sunsanvil]

Does anyone know if fuel consumed during idling, either in Park or at full stop when in Drive, is factored into the reported average fuel consumption readings?

On our 2018 the current/instantaneous reading drops to an absolute 0 in both cases so I'm wondering if they include that consumption in the average/trip reading?

[dogsridewith]

Zero IS the correct liters/mile reading when the motor is running and the car isn't moving.

edit: oops. meant to write miles/liter. (It's always been miles/gallon for me here in the states, and never had any fuel efficiency instrumentation besides a gas gauge.)

[sunsanvil]

That would be true it were Miles per Gallon, 0 being the "worst possible" (when idling).

But liters per 100km flips that on its head, where >15 (or however high the meter goes) is the "worst possible". When the car's instantaneous reading drops to "0" at a stop light, thats not "correct" (if it were, this would be the most efficient car ever made: consuming 0 liters of gas every 100km :) ). Incidentally, the reading also drops to 0 when DFCO is active, and indeed for those few moments that really is true (since fuel is effectively shut off).

So the question still stands: does the trip average ignore fuel consumed during idle, or does it factor it in as fuel consumed during the trip (distributed over the total kms traveled)?

[dogsridewith]

Your question is a good one. Liters/100km should read infinity when stopped and idling.

[DarkShadowFox]

the new yaris still burns gas when idling it has no start stop just has an average idle kick on and off type deal.

[CoryM]

I'm not sure what values the trip computer reads to calculate from. Eg: If they used the injector duty-cycle, they would have a very accurate measurement of actual fuel going in at all loads. But due to fuel quality/density differences, maybe it's more accurate for it to read other values and calculate from there.

You could reset your display, then do a bunch of throttle-snaps. If it were injector based, it should show up there. Also keep in mind that Idle and DFCO may be closer to 0 L/100km than 1; and rounding down because of it (DFCO does still use some fuel).

[DarkShadowFox]

I'm not sure what values the trip computer reads to calculate from. Eg: If they used the injector duty-cycle, they would have a very accurate measurement of actual fuel going in at all loads. But due to fuel quality/density differences, maybe it's more accurate for it to read other values and calculate from there.

You could reset your display, then do a bunch of throttle-snaps. If it were injector based, it should show up there. Also keep in mind that Idle and DFCO may be closer to 0 L/100km than 1; and rounding down because of it (DFCO does still use some fuel).

if you use the real time MPG calculator on the information display its delayed by like 1.5 seconds at full throttle you go from 30 to 18.5 MPG at 118 mph.

edit anything above 80 is like 18-22mpg

[sunsanvil]

the new yaris still burns gas when idling it has no start stop just has an average idle kick on and off type deal.

The question wasn't whether it burns gas while idling.

The question is whether said gas is factored in to the TRIP AVERAGE fuel efficiency.


You could reset your display, then do a bunch of throttle-snaps. If it were injector based, it should show up there.

Thats a good idea. Next time I reset the trip, I'll do so while in P and do a couple revs. That will at least tell us something. :)

I dont know, but I suspect that the trip figure is simply an average of the short-term interval readings (the "skinny bar graph") since the last reset. If I'm right, that would include those bogus "0" readings while idle (which might actually be read by the computer as 0, OR it might just be displaying 0 because "infinity" would confuse most people :) ).