PHEV are more efficient when the battery is down to 50/40% it allows the regeneration system to work more efficiently.
Public chargers need to be less than 35 pence a kWh, otherwise run in HEV mode.
The vehicles ECU has been programmed to run E15 unleaded petrol, there is zero benefits in using E5 super unleaded, stick with the cheapest E10 unleaded petrol.
Unfortunately I have suffered a brain injury and occasionally I get confused and often say the wrong thing.