I read a review of the 2012 Camry Hybrid that mentioned the car was fully warmed up and in S4 mode.

What is S4 mode?

 

They are talking about the 4 different stages of hybrid operation.

S1) Initial startup on cold engine (open loop on the O2 sensors and fuel trim)

S2) Engine temp is normal operating temp, catalytic convertor is NOT up to temp, engine will shut off at a stop after 3 seconds but the car will not go into EV mode (still open loop)

S3) Engine and Catalytic convertor both up to operating temp, the engine has gone thru a 3 second stop shutdown, the car will go into EV mode while running between 35 and 42 mph and decelerating. (closed loop on the O2 sensors and fuel trim)

S4) Full hybrid mode. Will occur at a stop and after a seven second wait, the engine will shutdown. At this point EV mode can be entered at any speed below 42 mph while you are not accelerating or going uphill.

 

Thanks Georgia. I am impressed by how well thought out and implemented the HSD is. I knew it was good when I bought the car, but the more I learn the more impressed I am.