 I've had my G37 for 3 months and have put 6,000 miles on it, which includes a 4,000mile /20 day trip, of spirited driving. It has had zero problems to date.  I'm very happy with the 28.5 mpg I have averaged doing 75 on the highway. I found the car to be very comfortable and was able to pack a lot more luggage then I imagined would fit in a car this size. 