actual mileage with "cold" engines?

MFD is correct. Engine is running to warm itself and to heat up the catalytic converter.
While it is warming it is also charging the battery, which is running the wheels.
Remember the car is maximized for mileage, but also to polute less, so converter has to be hot. I live in Minnesota, and I like to be warm as well, so engine runs a lot to keep the inside of the car warm, and mileage suffers. There are only so many BTU's of energy in a gallon of gasoline. Some BTU's go to propel the car, others do other things like heat, or cool, or run brakes, or run power steering, or lights.

 

I've never seen blue arrows. I only saw yellow arrows.
Are you sure about the color?

Anyway, you were seeing the Energy Monitor to know the energy flow.
In the initial warming up stage, the ICE does not provide any motive power, just warming up and no energy flow from the ICE.
Prius is driven by electric motor only, but it consumes fuel for the warming up, therefore your instantaneous mpg number was not 99.9 mpg.

Ken@Japan

 

As posted above, the MFD is correct. You may be coasting downhill, but you are still burning fuel to make heat.

Tom

 

I don't think this is an accurate statement at all.

 

Ken is talking about the initial warmup stage. In this stage the control system tries to keep the engine unloaded, so most of the driving force comes from MG2. Obviously, if we want to be technical, the ICE is always geared to the PSD, so some torque is being applied to the ring gear by the ICE. This means some driving force may come directly from the ICE, but it is minimal. MG2 carries the load, unless you use a lead foot.

Tom

 

Putting the MDF readings aside, the real mileage that I get with only short trips over a period of days is mid-30's, and the ICE seems to run all the time to warm up, except at a dead stop.

I have days when I have longer drives & mileage is mid-40's. But if I hit one of those stretches of time when I'm simply running local errands, even with a block heater, the mileage is low based not only on MDF reading but also by my keeping a log of each fill-up combined with both the computer MPG and the calculated MPG (plus lifetime MPG).

 

I see a similar effect with my 2006. For short trips, just 2 to 5 miles, 36 MPG. Average winter mileage appears to be in the 43 MPG range. Summer was 46.5 MPG.
I can (and do) make some very short trips ~ 2 miles, level and down hill in EV mode. The ICE never runs. I can manage the 5 minutes without heat.

 

Wrong. In EV mode ( you have to add the button on a US car) if you keep the heat off, the ICE will not turn on if you stay under 34 MPG, the engine load is not high, and the battery charge is above 2 bars.

 

Are you familiar with the stage-1a of warming up stages?
During the period, we see retarded ignition timing. It is after the TDC(top dead center), or minus number of BTDC, to make the exhaust hot.
Therefore, the ICE can't provide any motive power and Prius is driven by electric motor only.

Ken@Japan

 

Ken, So in stage 1a, if I pull away from a curb with a cold engine, and immediately go to 60 mph, you are saying that that speed is attained and maintained by electric motor only?

 

That's how I'm reading it too. So when I start it from cold and pull away quickly that's all on the electric and the engine is just warming up?

 

Ain't no way that car is going to go 55 or 60 on battery power only. With timing retarded, it will warm up faster, and not be at full hp, but that gas engine has to be helping propel that car down the road.

 

You can get lots of power out of an engine with ign after tdc, you just get lousy mileage...

 

I don't know how much is your "lots of power", but following is our observations;

	BTDC	case
1	-10	stage-1a	minimal output torque	hot exhaust to warm cat quickly
2	+5	fuel cut idling
3	+10	stage-1b and other idling
4	+15	normal cruising
5	+20	heavy acceleration	lots of power

Ken@Japan

 

I've never done such a stressful experiment for cold engine.
Why don't you do your own experiment by yourself?

Ken@Japan

 

I have similar issue regarding this topic: I find on cold mornings the MPG numbers on the screen will actually go down about .2-.4 points while the car is warming up. Even with the car not moving. Then the MPG will stabilize.

Is this normal with cold weather?

Thanks. Marvin

 

There have already been folks who've mod'd the prius to run up to 60mph via pure EV using existing traction pack / MG1/MG2 ... so "Ain't no way" your "Ain't no way" is correct by simply believing that there "Aint no way".



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