I had had problems filling the fuel tank completely. The gas pump would shut off, but the tank would register only 5/8's or 7/8's. The other problem that I had was that on two occasions, the engine faltered momentarily for no apparent reason. Others have had similar problems. So I took it to my dealer, Bill Ussery Motors.

Day 1: I was given a rental loaner (not a MB) and told to leave car overnight. The fuel pump was replaced to fix the engine faltering/hesitation. Fuel level sensor was replaced (with an updated unit supposedly, as this is a known problem) to fix the fueling problem. The car was ready at 3:00 pm, but I was back in the Keys and couldn't come back up til the next day.
Day 1 my cost: one day of vacation time and lots of money on mainland shopping spree :p in Volvo loaner (I upgraded from the usual loaner for $20.)

Day 2: Drove back to mainland (110 miles RT). Picked up c coupe. Noted that fuel gauge read about 3/8's tank, so I had lost a little fuel in the repair process (not surprising), but also the shop had not fueled the car to see if the repair had worked. Was assured everything was fixed so went home and gassed up in the Keys. Well, the pump shut off at 5/8's tank and I was PO'd (mostly at myself for not filling up before I left Miami). Called Charlie, my service advisor, and he said to bring the car back to Miami and he would go with me to a gas station so he could watch me fill the car. I didn't care for the implication, but agreed.
Day 2 my cost: 1/2 day vacation time and some chill pills.

Day 3: On the way up to Miami I noticed that the gas gauge reading was dropping rapidly. Somewhat horrified and not knowing what to expect when it hit empty, I downshifted to 5th and began to hug the shoulder (I was on a two lane highway with nowhere to exit). Within seconds the gauge fell to empty. Luckily nothing happened. The car keep running (I knew that it should have had at least 7 gallons of gas, but I didn't know for sure what would happen when the car "thought" it was out of gas). So I drove another 30 miles with the gauge reading empty. Once I realized that the bottom obviously had not really dropped out of the gas tank and that no malfunction messages were going to flash, it was no biggy to drive with it on empty.
When I got to the shop and told Charlie what had happened, he no longer wanted to watch me fill up the car. He had a rental car waiting, but since he thought it would take only 3 hours to fix, I declined the loaner. Told him I would go to breakfast and to call me when it was ready. I also told him I expected them to make sure that they could fill the tank completely and that I didn't mind paying for the gas since I would be using it. Three hours later the car was ready. They had replaced the fuel level sensors (both) and filled the car (no charge for the gas).
Day 3 my cost: 1/2 day vacaton. And I had a great breakfast at Coral Gables Cafe.

Yesterday I gassed the car up (it took me two weeks to use 1/2 tank - I know, I don't get to drive it enough!). But, the point is that for the first time I could fill it completely without the pump shutting off prematurely. Looks like it is fixed.

Overall impression of Bill Ussery's shop. Good. Everyone was courteous and helpful. Barring the hiccough of replacing a faulty fuel level sensor with another faulty sensor, the shop did well and seemed suitably chagrined at that misstep. Having to drive a long distance to get to the shop is my problem not theirs, it's part of the price of living in paradise. Geez, this post is long. Sorry, I'll try to pare it down a bit.
Deb

 

I too was surprised they didn't fill my tank after replacing the sensors to check if the repair was success. Luckily though, they got it right the first time.

 

Same here. They did not fill up the gas tank for testing. They also got it the first time.