I had the car in for its FSS A Service and the fuel gauge sending units (sensors) were replaced. It appears to be reading correctly now. Hopefully this is a long term fix. I did notice that the 2000 ML320 that we had as a loaner had a similar problem as the fuel gauge indicated 3/4 full when I left the dealer ship and 7/8 after we drove about 50 miles then full when I pulled into the dealers before returning it. Would the tank have overflowed if I drove it further? I did not encounter any problems with the dealer not wanting to do the service even though the FSS indicated 2300 miles yet to go. The oil had been changed at 5400 and now at 9000
with the FSS being reset this time. I will continue to change every 4-5K using Mobil 1 15-50W. I may even switch to Mobil 1 in the E next oil change.
Thanks to everyone that replied to my original post as the information was very helpful.
ItalianBenz...I was running late when we picked the car up so I did not get a chance to look at the old parts, although the tech seemed to indicate the same as what you had said.
He also indicated that he has replaced several of these in the last few months.

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Dave
88 300E 250K Sold
2000 C230K Totaled @104K
2003 ML320 156K Sold
2009 E350 4Matic Sport 46K Sold
2011 ML350 60K Sold
2014 GLK350 46k
2012 GL450 55K