I've managed to get my HCH into EV mode (not "electric only") fairly easily. Perhaps it's thanks to these warmer days. I keep an even pace on level ground or on a slight downhill. If the car takes the opportunity to force a battery regen, I put my foot gently on the gas and the IMA will come on, even though I'm still at 100mph on the instantaneous readout. This does not involve an Auto Stop of the engine. So long as I anticipate having an opportunity to do this before a regen opportunity (such as going down a steep hill, or braking for city traffic lights) I feel it will help bump up my overall mpg by a hair without severely draining the battery.