Stanley,

Yours was a very cogent discussion of the physics/chemistry of the TCH. Reminds me of a saying of Einstein's: "Put your hand on the burner of a stove for a minute; it feels like an hour. Talk to a pretty girl for an hour; it feels like a minute. That's relativity!" (No, he really said that!)

Anyway, while your argument seems unassailable in microcosm, some implications of it are unclear.

For example, I have always assumed that the HSD system would yield at least as high an FE under all conditions (and a higher FE under some conditions) than would a Camry of similar weight powered only by the Atkinson-cycle ICE (i.e., without MG1, MG2 and the traction battery). Do you think this is true? If so, why?

Here's my take on this issue. Suppose we take two cars - a TCH and a same-weight Camry with the Atkinson-cycle engine only - and drive them for say 50 miles at the same constant speed on a dead-flat course. Will the FE of the TCH be higher? It would seem from your analysis that it would NOT, but it would be equal to the "normal" ICE vehicle. Am I wrong?

Now, take the same two cars and have them travel from Point A to Point A on a closed 50-mile route that involves some hills. Will the TCH FE be higher? I think it will. Why? Because the HSD is able to recover energy from the regenerative phase that can be used for motive power, while the "normal" ICE cannot recover that energy because of heat losses during coasting.

Wadyathink?

OK...wait....just thought of another possibility. In the "flat-course" test have both cars follow the same speed profile, but vary the speed. I think this will result in higher FE for the TCH again because of regen vs. heat losses.

Bill
2007 Magnetic Gray TCH/Nav/Ash Leather
2002 Blue BMW K1200RS
2000 Champagne BMW K1200LT