 Bought the car used from a dealership in Dawsonville, GA. Tried to research as much as I could and found some issues with the 6's, but over all not too bad. Boy was I wrong... I guess I gauged too much off of the '07 Mazda 3 that my wife and I bought our daughter for graduating high school. We bought it in 2012 and have had no issues with it. I guess it's because it has the 2.3L 4 cylinder engine in it.. Well, back to my 6. It came with a new engine that was supposed to have a 3yr/36,000 warranty on it. Around May, the car started throwing codes and found out that the "Bank 2 was beyond threshold". My rear pre-catalytic converter was going bad. OK. I find out that the car has 4 catalytic converters on it. 2 pre-cats that hang directly off the manifolds and 2 past the Y-pipe. The cost to replace just one was going to be over $1000. I find out on a Mazda 6 forum, that the pre-cats cause premature engine failure. A bad design by Mazda. The material inside the pre-cats disintegrates and gets sucked back up into the engine by the EGR and scars the cylinder walls and blows the seals. Since my engine had been installed in October 2015, I figured I could get the issue fixed before anything happened. The best fix was to replace the manifold/pre-cat exhaust with an MSDS header set which deleted all of the problem areas. They were a bit of a headache, but I installed them with a friend in 2 days and the car seems to run ok. One month later, I start getting sluggish takeoffs and white smoke from the exhaust. Take it to a shop and I get told that I need a new engine. I talk to the company that the engine was purchased through and they have me call the company that had rebuilt it. Talking with the rep, I come to find out that this was the 2nd rebuilt engine that had been put in the car. The first was in August and it had the same symptoms. The rep asked it the cats had been replaced before I bought it and I said no and that I just replaced the whole exhaust in May. That they looked like the same ones that were originally installed on the car. I was told that they wouldn't be able to honor the warranty because the previous owner (the dealership) said that they had been changed before. When they got the previous rebuilt engine returned, they did an inspection and found glazing and scarring on the cylinders and cylinder walls consistent with debris from the pre-cats. They said they had pictures to show the damage, which they sent me so that I could open a BBB case against the dealership because they new the results days before selling the car to me. I wound up buying a new rebuilt engine for $2400 and the labor charge was $1000 and the car, which I have dubbed "Killer", is on engine number 4... Pray for me...