My 2013 A6 3.0T Engine Has broken down. Please advise
 

Hi have a 2013 Audi a 6 3.0T Prestige. I bought a brand-new 5 years ago in September 2013. It has ~49,000 miles on it. I had Audicare on the car. It had received all its regular maintenance. It had not given me any problems up until now. The problem started last Saturday while driving on the Freeway, 20 mins in, the car started shaking on any attempts to accelerate it. 5 minutes later it completely stopped and would not start. The EPC light came on. No other lights came on ever. The ignition was making a sound as if it was trying to start but it would not start. (I tried multiple times)


The car was towed to a dealership. They looked at it and said that there were multiple misfires from all the cylinders especially cylinder 1 2 and 3. They said there was carbon residue around the spark plugs. They also said that their technician heard something inside the engine with a stethoscope. They need to do a complete engine tear down to diagnose the problem. Just the diagnosis cost itself is around $5000.


I am just completely surprised that the car engine was in such a bad shape with no prior events. I just wanted to get some feedback from people here to get an idea what could have caused this. I am not sure if I can completely trust the dealership also so I will probably get a second opinion as I am looking at a repair cost around $10,000.


A few things of note. #1 the car had given me no problems up until June 2018. At that point I had the fuel line changed by Audi as per their recall. After the service every once in a while the car would stutter for 1-2 seconds when starting the car up and driving. The stuttering never happened after the first 5-10 seconds of driving and only lasted 1-2 seconds. I guess now in hindsight I should have had it checked because it was abnormal. I thought it was maybe the transmission slipping a little bit. Could anything with the fuel line change have messed up the timings to cause this problem with the engine?


#2 The night before the problem occurred I went out to eat at a restaurant. When I came back the car's gas tank cover was open.Part of me was suspecting that there could be potential some foul play. May be someone put some water into the gas tank. However Audi said that is unlikely.


I guess I just came here to get any advice from the people on this forum. If anyone has experienced anything like this before? Anything else that I should look out for? Or am I at the mercy of the dealership And have no choice but to make such an expensive repair. The car is probably worth around $20,000 and part of me is wondering if it is even worth it to go through with the repair at that cost.