Mechanic	Rate	Formula
Consumption	1 unit every 2 frames	~25 units/sec at 50fps
Refueling	4 units per frame	~200 units/sec at 50fps
Full tank duration	~10 seconds	255 / 25 = 10.2 sec
Full refuel time	~1.3 seconds	255 / 200 = 1.3 sec

Consumption rate does NOT depend on scroll speed. Low fuel warning triggers when <$40 (top 2 bits clear). Refueling only occurs when plane is centered over depot (not banking left/right).