Thanks @kezo Yes, I was using ‘Auto’ mode on longer journeys previously, but changed to HEV mode when on the motorway yesterday as was suggested. When in Auto mode it seems to prioritise EV driving, including on motorways, until the battery depletes to 15 or 20%, when it then switches to HEV mode. However, thinking about it, when it switched to HEV mode when using Auto, it seemed to also charge the battery but only up to about 2 miles EV range, when it would then deploy that 2 miles in EV mode. That process kept repeating. Actively selecting HEV mode prior to battery depletion (as I did yesterday) seemed to result in the battery being recharged continuously until it was full again, which didn’t seem sensible.
I’m doing the same trip again on Thursday so will revert to using Auto and see what happens once the battery depletes, keeping an eye on the instant mpg and how often the engine is recharging the battery. As is often said, it’s a big learning curve but, to revert to my question, I presume you are not aware of a setting where you can stop the petrol engine recharging the battery above and beyond the 15-20% minimum?