S4 Strategies....

I'm curious about this too, since the driving in our area does not call for stops. We only have one traffic light in the county, and that one is 25 miles away. My typical Prius trip involves leaving the driveway cold, traveling two short blocks at low speed, then going 25 miles at 55 mph before the first stop. There is a stretch of 30 mph road through another village 15 miles away. I know on some occasions I have traveled that 30 mph zone on electric only, but perhaps that only happens if I have stopped before. I doesn't seem like that's the case, but I haven't studied it formally. I wonder if it is possible that I am getting S4 without the six second stop?

Tom

 

I have a handful of stop signs on the commute routes, and I also do the slow roll when I can do so safely. If I have to stop, traffic behind me often prevents sitting long enough for the idle check.

These days I generally just wait for the idle check until I know I have to stop anyway. My regular commutes have enough red lights along the way that one of them will catch me long enough for it. Meanwhile, the routes I choose generally allow slow enough speeds to use the EV switch, so there's no urgency. And if not, they allow sub-41 MPH glides.

Before the days of the EV switch I would be more eager to get her into S4, stopping at lights or stop signs that I now try to optimize approach glides towards. Occasionally I would use a parking lot if I could pull into it at a slow glide. I still do that from time to time for certain non-commute trips when there is uncertainty about upcoming opportunities to do it sitting in a travel lane. The main motivation now is to eliminate the nuisance of continually pounding the EV button.

 

Not a hypermiler, I do drive efficiently so my strategy is regardless of weather, cut through neighborhood, ~1.7 miles, using a maximum speed of ~27 mph and coasting in "N" to minimize fuel burn.
When I reach the last neighborhood segment, I'll ramp up to 35 mph and coast down in "D" to see if the ICE will auto-stop:

1. It does not autostop - the coolant has not reached 70C so the ICE can not transition into S4. I stay stopped in "N" until the light changes and continue my commute using 35-38 mph and looking for evidence of S3 autostop.
2. Does autostop - means holding the brakes on, I pulse the ICE to get it spinning. If MG1 rpm does not drop within seconds to 3,500, I shift into "N" and wait until it does for at least 10 seconds. Then I shift into "D" to see if it will S4 autostop. If not, I go back to "N" and try again later in the commute.

Until I know I'm in S4, I try to use 35-38 mph commuting speed since in S3 it will autostop. Speeds below ~32 mph, it won't autostop in S3.

BTW, there is some evidence that stopped in "N" with the ICE running may allow the S3 to S4 trigger to occur but in "N", it can not stop the ICE. This is very subjective data that is what I think I'm seeing.

Bob Wilson