I just took my cat to the petrol station to give it a try, and have to report that not only does she not have any indicators like this, she also was vehemently opposed to being refuelled and scratched me up badly.
A friend of mine took their cat to the gas station, after refuelling the cat took a couple of steps and dropped on the floor. I was like "Damn, already out of fuel? What did you say the milage was?"
If there is an arrow by the gauge then that is the door, but a lot of cars don't have that arrow. If you are going by the handle on the gas gauge, that means nothing. I've been in plenty of vehicles that didn't have the arrow, and the handle was not on the side of the gas door.