46 MPH is the new threshold for STEALTH

I'm finding with GPS confirmation that the indicated speed is 1 mph high at speeds 50-80 mph. However, the trip meter mph is dead on.

Check a stretch at cruise control set speed and resetting one of the trip meters. The indicate will be about 1 mph higher than the trip meter value on my Prius III.

Bob Wilson

 

I have found the 1 mph high indication to be case on mine also when I compared with my Garmin. Used cruise control on the first commute but I get better results without CC. I am new to the Prius game since I just got mine last week. Anxiously awaiting my special license plates so I can use the HOV lanes. I noticed the trip MPG increasing while stuck in traffic the other day(whoopee!) but I would really rather be moving.

 

OK, so I'm cruising at about 60 and get out of cruise control and start slowing, and I see on the diagram of where the power is going that energy from the wheels is going to the electric motor and thence to the battery. But NOTHING is showing either way from the ICE. The ICE sounds to me very quiet, at least under the rest of the cabin noise.
When I see this, I notice that the speed is about 58 MPH, which is well above the 46 limit everyone here is saying exists for stealth.
Is the picture lying to me, and something really is going on with the ICE?
Or is there just something I'm missing completely here?

 

You were looking at "ENERGY MONITOR".
It shows the correct energy flow, and it can't be used for the ICE running status monitor.
To see the ICE status, ScanGauge or my ICE running monitor LED will be your friend.

Ken@Japan

 

It's not exactly lying to you. The engine has to spin above 46mph, but it does not have to be burning fuel to turn over. The transmission can mechanically turn the engine over without any fuel being injected or the engine actually contributing any power. The 'engine' arrow on the Energy Monitor screen indicates when the engine is actually producing power, not just turning over.

However, with the engine turning, it does pump air back and forth, so it's wasting some energy. It spins quite slowly - I believe under these conditions it is allowed to spin more slowly than its minimum 'running' speed - so it doesn't waste that much energy.

This behaviour, using electric power with the engine spinning but burning no fuel, is normally called 'warp stealth' by enthusiasts.

The car generally prefers to actually burn fuel at this speed because it's starting to get towards its most efficient region, and the efficiency of the electric drive gets worse the more power that goes through it. Above 46mph it's generally more efficient to just keep the engine on than the average efficiency of turning it on and off. Below 46mph the averaging works out better despite the charging/discharging losses.