Does the CLK gas gauge tell the truth? Or is there a contingency to prevent people from running...

I notice that when I fill up my tank, my gas gauge shows a full tank at 16.4 gallons. Then when I dive the car down to 0.0 gallons and then fill it up, I can only fill 14.5 gallons, indicating that there is still 1.9 gallons left in my tank.<br> <br> I've repeated this several times and it is consistent.<br> <br> Anyone else notice this?

Wish the tank would be 21 gallons.