Toyota’s Irv Miller jumps into Series-Parallel debate again! Now with new definitions!:

Over at the Toyota Open Road Blog, Communications VP Irv Miller has chimed in again on the whole parallel vs series hybrid debate, this time with some fresh definitions.

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Perhaps Miller’s most interesting, if dubious, point comes when he tries to redefine some hybrid terminology. The series hybrid is simple: it refers to a battery-powered vehicle with some kind of range extender. Miller defines a parallel hybrid as a system like the Honda IMA that does not have an EV-only mode. Most other people in the industry would call this a mild parallel hybrid, since both the internal combustion and electric motors provide torque to the wheels. In function this is little different from the GM belt-alternator-starter hybrid system.

Referring to Toyota’s own Hybrid-Synergy-Drive system, he now terms to this as a series/parallel hybrid system. The series portion comes in because the system can drive the vehicle from the electric motor only, in addition to using the combination of the ICE/motor or just ICE. Ford, GM and everyone else using such a system just call this a strong parallel hybrid. This move of changing the terms of the discussion really comes off more as obfuscation of the argument than advancement. It seems like Toyota may be regretting opening this can of worms in the first place. At least Miller does acknowledge that their is no one right answer and that their is room for multiple solutions for different applications.

Someone should remind Toyota of the Rule of Holes: When you’re in one, stop digging.

This is really getting absurd, and has proven another old guideline, that any argument that goes on long enough eventually devolves into semantics.

I should jump in here and explain how I use these terms, even at the risk of making the situation worse. In short, I agree with the author above (not Miller), on what’s a parallel vs. a series hybrid, and within a parallel, where the dividing line is between strong and weak variants.

I would agree that the Toyota system is this new thing, a “series/parallel” hybrid, only if [1] the battery can be charged from the engine (i.e. not just regenerative braking) and [2] the vehicle can drive some non-trivial distance, say, 10 miles, purely on electricity.

I don’t make any distinction between series hybrids that start/stop the ICE as needed from those in which the ICE runs constantly. I’m sure that there’s a terminology difference there, or if not, someone will come along and create one shortly.

I think what we’re seeing here is Toyota not liking the fact they’re on the wrong side of the series vs. parallel divide, and deciding to address it in the very short run with PR moves while the engineers work behind the scenes on something more substantive for public consumption in a few years.

Series hybrids, especially with greatly downsized ICE’s capable of running on E85, could make such an enormous difference in the petroleum intensity of our transportation that I think they’re inevitable. The only way I don’t think they will arrive and become a dominant part of the market is if we make basically no advances in battery technology, or we make such huge advances that we can leap straight to EV’s. I strongly doubt either of those scenarios will come to pass.