If its what i think you mean then its the charge indicator … when the band drops, the petrol engine cuts in to recharge the battery and, (depending on how you are driving), then the indicator gradually builds up to the top of the arc. If you are driving on the flat at 30- 40 mph you are more likely to get longer periods of electric power … if you are climbing hills with your foot down the petrol engine kicks in a lot quicker … I get around 58 mpg and i go up and down hills quite a lot !

Clive
Thank you, that make sense. This is the first Toyota and I love it, it is good that there are people like you who are helpful, not like my last car a H………a who Customer Support could not care.
David

Glad to help… I’ve had mine since March 22 and still no idea what a lot of the switches or features are …. Even the salesman said he wouldn’t bother telling me how it auto parked as I would never remember… or use it. I did manage to switch off the ‘lane keep assist’ function as I found it unnerving and I guess I haven’t needed the things I don’t know about. To date I’ve had no problems with the car and am very happy with it.

Thank you, yes I echo your comments.
D avid