There aren't really 2 different tanks...it's 1 tank that is bifurcated (has hump that creates 2 sides). The siphon jet sucks the fuel from left side (which is larger than the right side on the e53...unlike the e38/e39 where the 2 sides are basically equal)...to the right side which is where the fuel gets sent on to the engine.
So, Test 6 should show a greater amount of fuel (on a full tank) on the left sde...then it should decrease to "0"...then the right should start to decrease as you continue to consume fuel.
