https://en.wikipedia.org/wiki/Brake-specific_fuel_consumptio...
This is possible (and done) in any automatic, but in hybrids it was taken to the extreme, with electric motors covering for situations when either the RPM or torque are not where desired.
In fact, my experience is that during highway driving it's actually slightly off the optimal point, charging the battery in the process. I speculate that it's so that the surplus power can be released immediately by just making the electric motor stop acting as a generator and go into, well, motor mode.
It does get crazy mileage and drives well so I can't complain. They are more expensive than standard cars though and you can't leave it in neutral which is a problem in some car washes.
I always found most explanations of Toyota's Power Split Device too abstract, until I found this page where you can play with the sliders to see how the power is actually split between the ICE and the MG1/MG2 electric generators: https://eahart.com/prius/psd/
Actually, another thing was that the visibility out of the Sienna seemed quite bad.
Visibility is fine, comparable to other minivans and much better than a few older models. It no longer has rear vent windows, which is a pity.
The software for the infotainment system is horrifying. Everything else is quite good.
chancitag•1d ago
But. The other points made felt muddled or even contradictory. I either didn't follow the TC guy's explanation closely enough, or the script could have used another pass.
Szpadel•40m ago
computer could use Otto cycle in case more power is needed in rare situations
bluGill•34m ago
Tade0•27m ago
Toyota introduced this exact behaviour with their "Variable Valve Timing-intelligent Electric" (VVT-iE) system:
https://toyota-club.net/files/faq/16-01-01_faq_vvt_ie_eng.ht...
It uses an electric motor to control intake valve timing.
nemomarx•33m ago
I've seen some modern hybrids just have a visualizer for this on the dash to encourage you to coast more and things, which seems about as helpful in understanding it too.