Bought used. Drove for a week when this first happened. Still under warranty so had it towed to dealer in Halifax. Three weeks to hear that a plug was bad. Changed out all 4 plugs and ignition coils. 5 months and had the same exact fault. The car shook, misfires and quit. Changed one plug on the misfiring cylinder, all good again. Back to dealer to complain, no warranty left. They checked it out this time, and found some scoring in the cylinder wall. Charged me 505 bucks and advised me to get rid of the car asap. I can't do that to somebody. Anyway, I don't know why the good investigation didn't happen while I still had warranty, but this is where I'm at. I've been told that there may be a class action being started to address these problems with the M274 engines. I can only hope.