Time to pull out my old 10G plots. I know there are minor updates in 11G, but the basic ideas are the same. This is the efficiency map for my 2018 HAH engine:
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There is a lot going on here, so let me explain. Engine speed and torque should be self explanatory. Since RPM*TORQUE=POWER, we can determine the power being generated at any point here. Which is the more important number. It is labeled on the right side in horsepower, and follows the gray curves thru the plot. (Sorry for the mixed systems of measurement.)
The colors in the center indicate how much gas is used to make that power. The best is 208.1 grams for each kiloWatt-hour, which is 40.6% efficiency. It happens at 2000 RPM (or 54 mph in Engine Drive) and 34 HP. This is where we would like the engine to operate all the time. The blue line represents the best efficiency
at each RPM value.
The disadvantage of gasoline cars is that, for the car to have enough power for acceleration, this "sweet spot" has to be in between the power needed to maintain speed on a flat road, and the power needed for acceleration. Cruising power is shown by the black dotted line, for the gear ratio we have in Engine Drive. A conventional car, with a shiftable transmission, would move that line right or left so that it crosses the blue line near the power requirement.
And that's the problem. To cruise at 45 mph, the black line says that our car needs a little under 10 HP. That crosses the blue line (the last blue dot on the left) at about 230 g/kWh, or 35% efficiency. In a gas-only car, this would be lower since the engine has to be bigger. It would operate at about 30% efficiency. I'll return to this number.
But in our hybrid, the system will move along the blue line to one of the purple dots, as indicated by the yellow arrow. The extra power generated will be used to charge the battery. This will be used later, either in EV Drive or to move back to the purple dots (from either the right-side blue dots of the higher yellow dots). That will also improve efficiency. The down-side, is that using the battery to save, and recover, this extra energy has maybe a 25% loss. So, while the power you use directly is 40% efficient, the power you use indirectly is 30% efficient. I've gone on too long, but the yellow dots do something similar in Engine Drive.
And this finally gets to your implies question. When accelerating, the absolute best thing to do is to accelerate at a rate where you are neither charging, or discharging, the battery. This way, you get it all at 40% efficiency, and none at 30%. I've never tried to watch that, but my guess is that you come close to it with what you describe. But it can only apply easily at the slower ranges of speed.
They do the same thing. When you press the brake pedal, the computer uses what is called "blended braking." It will apply as much regen braking as is both possible and safe, then add friction braking. If you use just the paddles, the system relies on you to determine when to add the friction brakes. You can train yourself for how much room is needed to slow down most efficiently with the paddles; but once you master that, the pedals are just as efficient. (I really do feel like Dr. Seuss when I talks about pressing pedals vs. pulling paddles.)
Pulse-and-glide is essentially doing the same thing as moving the dots around as I described above. The exception is that our hybrid, unllike some others, does not have to speed up and slow down to accomplish it.
