I somehow knew I wasn't alone with this problem. It seems that MB fuel gauges are crap. Funny. We have an ancient Ford ('65) truck up on my stepfather's farm which still has a perfectly accurate fuel gauge - he uses it to gauge his mileage. Now why can't MB come up with something a little more reliable? I for one am sick of explaining to anyone who borrows my car my little system of fuel monitoring...
"OK, now watch the tripmeter. When it hits 500KM, watch for that little reserve light. When the reserve light comes on, you've got about 35 KM to find some gas. Oh, and ignore the needle, it will be doing a nice little dance for you..."
This explanation is almost always followed by a sarcastic remark by my friend(s) about Mercedes quality, etc. and how their little Toyota or Mazda has a perfectly working fuel gauge.
I'm going to write to MB and ask them about this problem. Don't know what good it will do, but it is annoying that they have never addressed the issue (unless they have and I don't know about it). Do they not consider fuel a big issue? I mean, the stupid and useless "economy" gauge works just fine!
Or perhaps, as James said, we are all supposed to drive above 1/2 all the time with our only worry being where to store our big, fat, bulging wallets.