There is one thing which simple characterizations like this miss. That is the effect of fuel not lying level, given that at any instant the car may be accelerat

There is one thing which simple characterizations like this miss. That is the effect of fuel not lying level, given that at any instant the car may be accelerating longitudinally and laterally, not to mention driving on an inclined surface. So when the fuel is very low, at any given moment it may all be pushed into one end, or corner, of the tank, away from the pickup.