ChrisMiller wrote:Other than those special circumstances, use of Charge means burning extra petrol to generate electricity and store it in the battery for later use - since there are significant inefficiencies at each stage of this process, this isn't particularly cost-effective. You can read lengthy and erudite discussions on this forum about other circumstances in which Charge may be advantageous - but since the gains are marginal when/if it works, and the costs are significant (in unnecessary fuel consumption) when it doesn't, I choose to leave it well alone.
That's not really true. The car runs in what is effectively Charge mode roughly 50% of the time when the battery is showing empty or when the Save button is pressed. So saying that the default mode of the car 50% of the time is somehow worse than another mode is meaningless - the PHEV either charges in Save or low battery, or it stops.
Does Eco mode only remap the throttle, or does it turn down AC or heating output too?
Going back to the OP, drawing high power from the battery is generally accepted to be bad for degradation. So high speed on a dual carriageway would usually fit into that category. To help preserve your battery health, it might be better to run Save when the car would be drawing high power from the battery and using EV at slower speeds. That said, it is most fuel-efficient to arrive at your next charge with an empty battery. And don't forget that pre-heat is your friend on a cold morning,as it means you can effectively use mains power to warm your car rather than the ICE.