A typical drive starts with the fuel tank filled to a comfortable level. The dashboard fuel gauge shows the needle positioned safely above the empty mark, indicating plenty of fuel for ordinary travel.
With each mile driven, the needle moves downward across the dial, tracking the decreasing fuel supply.
The situation remains in this familiar state until the fuel reaches the reserve boundary.
At that precise instant, the low fuel warning light turns on, its steady glow appearing on the dashboard.
Immediately before, the dashboard shows just the gauge needle, with no light illuminated.
Immediately after, the warning light is visible, marking the change to reserve fuel level.
The car has now crossed into the low fuel state, distinct from the prior condition.