I always fill up at 1/4.
​​​Still getting used to how much cheaper a 17 gallon regular tank is when compared to a 22 gallon premium tank I've been filling for the last couple of years, going from $40 to $25 is significant and about the same regularity...

 

I've only gone as far as 60 km remaining range before fueling up. At this point the yellow fuel warning light goes on. I sometimes forget about filling up because the hybrid can go for over 600 miles on a full tank.

With the hybrid, you're never supposed to run out of fuel because it's possible to completely drain the traction battery. I don't know if the battery can be damaged but the car won't start afterwards and you'll need to flatbed it to a dealer.