DesertDog — Your observations hit on an important point. In my calculations of the increased power required from the ICE during the battery-recharge phase, I was forced to make a somewhat incorrect simplifying assumption — namely, that the ICE was operating at the same efficiency during the 40-miles per hour recharge phase as it is during normal ICE-powered driving at 40 miles per hour. This will be wrong, since with the higher load at the same road speed the ICE's efficiency ought to be somewhat higher. I don't believe that it is easy (or even possible) to compute the "correct" figure from the information provided in Miller's paper. If you have any ideas about resolving this matter, I would be interested to hear them.

In the absence of a "correct" ICE efficiency figure for the recharge phase, I used the same figure as that given by Miller for normal ICE-powered driving at 40 miles per hour: 0.69466 (= Pem/Pe on Slide #52). I also assumed the same mechanical-to-electrical loss factor for the battery recharge phase as for the EV-powered (discharge) phase: 0.91*0.94 = 0.8554 (same Slide #). The overall discharge-recharge mechanical-electrical-mechanical loss factor is thus 0.8554^2 = 0.7317, and when combined with the assumed ICE power efficiency factor of 0.69466, yields an overall loss factor of 0.50829. Dividing the required MG2 power of 5 kW by this factor gives the needed additional ICE power of 9.84 kW during recharge. (My corresponding calculation was parsed somewhat differently in Post #29.) This gives the total ICE power number of 6.47+9.84 = 16.31 kW that I used in my calculation.

I agree with you that I indeed misread the labelling of Miller's BSFC curves, and that the number I should have used for the 40-miles per hour recharge phase at 16.31 kW is 210 g/kWh. Recalculating my numbers using this figure leads to the following revised final bullet in Post #125:

• 0.5 h (20 miles) of EV @ 5.85 kW => 2.925 kWh from the battery during the pure-EV phase (no fuel used), followed by 0.5 h (20 miles) of ICE power @ 16.31 kW => 8.155 kWh => 1712 g of fuel => 2.314 L of fuel => 7.19 L/100 km => 32.7 mpg during the recharge phase, giving 3.59 L/100 km => 65.5 mpg for the overall trip of 1 h (40 miles).

This is in agreement with your calculation, and is effectively the same as the 66.6 mpg number for normal ICE-powered driving. I don't believe that we have the data necessary to resolve this matter. The TCH's electrics being even more efficient than the Prius's would render the results a wash for the TCH as well. This is indeed what I found in my experiment (Post #48).

You could try doing calculations for a lower EV speed (Miller gives numbers for 30 miles per hour in Slide #50) and the same 40-miles per hour recharge speed as I used, but will I think be stymied by the same lack of data for the recharge phase as I found. I'd be most interested to learn what your calculations reveal, but yes, I would expect better results. I chose to use as nearly as possible the same speeds (~40 miles per hour) for both the pure-ICE, pure-EV, and recharge modes, so as to make the comparison as fair as possible (the fewer variables being altered the better). You still need to convince me that "EV rocks!" but it may not suck as much as I first thought!

Stan