hearing all your comments, my fuel gauge doesn't seem to be a Mercedes gauge!! mine is a 85 190E 2.3 with 126K miles - the fuel gauge is rock steady all the way till empty. It may not be perfectly linear, but is remarkably consistent. Over the years, now I know EXACTLY how much fuel the tank will take depending on where the needle is (+ or - quarter gallon). On a 14.5 gallon tank, at 3/4 the tank has 10 left, at 1/2 it has 7 left, at 1/4 it has 4 left (so its not exactly linear), at the red light it has a little over 1.5 gallons left. The amount I fill up is remarkably consistent with where the needle is!
Now that I have said this, wait till my gauge starts dancing all over the place starting tomorrow!!!!!