[phibz]

On cars without the arrow they often follow the convention where the gas filler handle is depicted on the same side of the gas icon as the filler door is in the car.

[nutjob2]

First time I've heard of that convention.

[snozolli]

Because it's a myth. It used to go around Reddit regularly.

There's even a Snopes entry:

https://www.snopes.com/fact-check/fuel-icon-foolery/

[whiteboardr]

That was the original idea on how the icon should be used but obviously too subtle.

Moylan basically added a modifier icon for clarity.

[pants2]

I've heard that the gauge always points towards the side the cap is on when pointing to empty

[anjel]

Far too subtle