Originally Posted by noisebeam
This is true and I almost commented on this, but it is not common. Also while the engine often does not run at sub 25mph speeds, it is not clear to me if the engine shuts down when coasting down hills, I know that the display shows no engine power being used, but a full shut off is not obvious. (often the engine keeps running to charge the battery, even if it is not applying power to the wheels). I do know on one long 5mi hill I sometime drive down at 65mph the computer shows no engine power going to wheels, but also the engine does not shut off as it shows it charging batteries.
I encounter hybrids all the time on my commute and on rural roads and never once was surprised by one - but someday I will be as I've been surprised by normal vehicles behind me, sometimes wind noise, directio or other ambient noise is enough to mask a conventional engine and tire noise.
Al
You can feel the IC engine shut off (this occurs with mine every day since I live on a large hill). Now, the engine doesn't stop turning, but there is no fuel being burned in it. At speeds under 30 mph, the engine will frequently shut down as well and the car will run on battery power alone. The algorithms Toyota uses are pretty complex and don't key off of the speed of the car, but rather the speed, power, and torque of the IC. The gearbox is a planetary gear linking two electric motors (a traction motor on the outer ring of the planetary gear set, and a smaller motor on the sun gear) and the IC (attached to the planet gear cage). This effectively makes the main traction electric motor and the IC independent and eliminates the requirements for a transmission in the traditional sense. And Toyota makes full use of this ability to completely shut down the IC during normal driving when it makes sense. The only reason why the IC is kept spinning is to limit stresses on the bearings and gears.
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