[tom66]

100% charge on the GTE is around 94% real battery charge.

If you are going on a long trip fully charge the car.

For shorter journeys aim to charge 25-30% more than expected so 10 mile trip go for 13 miles charge.

This will improve long term battery pack life.

 

[tom66]

No! You might faff about, as you describe, in an all electric car where you can fully charge and fully discharge the battery. In a PHEV you can’t fully charge or discharge it (Golf Mk8 13 kWh total, only 10.9 kWh ever available).

Come home, plug in. Unplug when charged and drive. Simples 👍.

Regardless of the protective buffer, it is still a fact of Li-Ion battery life that if you limit the peak charge the battery life will be preserved.
At 94% the pack is at 4.15V per cell. The general rule is above 4.00 ~ 4.05V the life of the pack begins to be shortened by transitioning into that higher energy state.
So in general limiting the high charge state will be better. (Very low charge is only a problem at cold temperatures.)