Those are all good comments! Based on my recent FE experiments, ag4ever, I agree that increasing the capacity of the battery would not help increase FE. It would only allow a greater range in pure-EV mode. What one needs is some way to prevent the ICE from recharging such a larger battery, so that one can make use of cheaper electricity rates to recharge it overnight from the ac mains. The TCH hybrid control system would need extensive re-coding to allow this. I don't believe that Toyota would provide the needed information to outside parties. Without reliable batteries of much higher capacity, one would have to fill the vehicle with batteries to increase the pure-EV range sufficiently to obviate the need for a gasoline engine as a means of propulsion. The recently-announced GM plan is a series hybrid — the ICE can't drive the wheels mechanically. This must be less efficient than the Toyota system whenever you actually do need the ICE to recharge the battery. Moreover, if it is to be able to recharge the battery at the rate at which the motor is depleting it, so that you can keep on driving, it has to be a substantial ICE too. This GM idea doesn't impress me. Maybe it will never see the light of day in the form announced.

Orcrone, your pure-EV experiences mirror mine.

ag4ever, I think the main reason for limiting the speed in pure-EV mode is to prevent MG1 from over-revving and mechanically damaging itself. The planetary gear ratio makes MG1 spin very fast when the ICE isn't rotating. If this is correct, then re-programming the ECU isn't an option.

Stan