Most of the time I drive in the city in EV mode. Every now and then, when accelerating too hard, the car quits this mode and returning to EV takes a while, sometimes 10-20 seconds, sometimes more. But yesterday, although almost fully charged, it didn’t want to return to EV for the whole drive home, more than 10km… The average consumption was quite high too, 14l/km! Tried switching to Eco, EV, Save, turned off the engine, waited, turned on again, nothing… Even if the EV light was lit, the blue notch was not displayed and it wouldn’t go into electric mode… This morning, the car started with the petrol engine again and didn’t want to switch to EV mode. After driving for a while, just when I wanted to call the dealer, the EV notch appeared and all was fine, drove in electric mode all the way to work (7km). While the petrol engine was on, the graphics were showing that it was charging and also the start stop system didn’t turn off the engine at lights…

The patronising answer you will likely get from the dealer is "it's complicated"!!

It's infuriating when the engine starts when you start the car in EV mode with a fully charged battery. I paid for the blummin silence and waftage!!

If you accelerate hard and it needs the engine too, then the engine will remain on for a couple of minutes (presumably to warm it up properly) before it drops back out.

And when the car has a complete brain-fart like the one you describe, I just put it down to an overload of tech.