Motorway or running fast use HEV mode, try and keep EV for local or 30/40mph , ideally you want to return home with a depleted battery. With a PHEV when the battery is over 80% you will gain nothing from regeneration, I run my battery down to about 50/60% that way I get maximum regeneration, a depleted PHEV gets maximum regeneration, hence why these HEV are so efficient. It took us a few month to get the best out of the PHEV it is a learning curve.
Thank you 🙂 Going away in a few weeks, so will try this, along with coming home from parents, switching to EV as I go up over the Brecon and up the long steep hill to home. A learning curve indeed!
1. At the start of your journey use EV mode and deplete the battery down to 50/60%,
2. Switch to HEV mode and use EV mode for 30/40 mph sections only.
Over the Brecons use HEV mode (I take it your vehicle has paddles, uphill zero, downhill use maximum regereration), going downhill especially in the Brecons the camshaft timing will switch to the Atkinson cycle  (your ICE unit will use no fuel going downhill)
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.