Well few weeks ago, I asked to change out the original fuel filter and got MB to partially pay for the whole fuel system upgrade. While the dealer opened up everything, they replaced the fuel pump/sending unit as well since it's covered by MB's goodwill. So all is good except that the fuel gauge drops like dow jones. I took it back one and they replaced the fuel pump/sending unit already. I was just trying to see if anyone had similar experience and can share what the dealer did to fix it. I will let it drive for few more tanks of gas to see if it will magically heal by itself.