I was driving to work today, got about 14 out of 16 miles there and the check engine light started blinking and the car was stuttering when trying to drive. I managed to get to work with it stuttering the whole way and called up a local well reviewed mercedes mechanic to take a look at the car. When I brought it in, he checked the codes and it indicated misfiring on all cylinders. He believes it was just some bad gas.

Has anyone else had this happen? I turned the car off and on a couple of times and it still kept doing it. By the time I left work a few hours later to have him check it out, it appeared to be driving normal but still had the check engine light on.

It appears to be fine now, although does seem a little louder than before. I'm wondering if I could have damaged a CAT with the misfiring?

 

Are you on stock tune?

 

All stock

 

Different reasons for misfires: plugs, coilpacks, low pressure in the cylinder, faulty MAFs, leaking head gasket, etc... or just bad gas.
Usually you start with spark plugs. In your case your tech said all cylinders were misfiring which can be odd if it's all your plugs that are being bad at the same time. Could be your fuel pressure valve as well being bad. Another member had the issue on his C63.
I doubt you damaged your CAT. Try to empty that tank and pour it better fuel to see. GL

 

He said to put in gas without additives so I found some cheap crappy premium fuel to try, I normally fill up almost exclusively at costco as they are near my work and rated top tier. Otherwise I use Valero near my house that is top tier.

 

If you did get some bad gas, you may need to replace fuel filter. I also use top tier gas. Shell, Chevron, BP. but still I had a similar problem with my wife's car ( Hyundai 4.6 V8) and it was the gas.

 

You are a lucky man, my wife won't go near a Hyundai. I almost bought a Genesis instead of this car. If I had kept the Corvette, I was going to get the 5.0 R.

The extended warranty should cover everything if anything is wrong. The mechanic said fill it up and beat on it for a bit, he doesn't think the problem will return. I've never had a problem with any gas before in 20 plus years so this was a first. I did find some posts out there from the past couple of months claiming costco gas messed up their cars. Hopefully it was just isolated occurrences as they are supposed to be top tier.

 

Reliability wise the our Hyundai Genesis has been near perfect. Just past 150,000 mile this week and only one repair cost and that was a sensor in the emission system , 285.00 at dealer. Still has oe rear brakes. Front brakes lasted to 130k miles. But the AMG is so damn fun.