I owned a 2004 6spd coupe and currently have a 2006 6spd coupe. Can’t speak for the G37 other than I had the same motor in my 2010 370Z. It was and is an extremely reliable car. Motors on the 2009/2010 did have some oil burning issues and steering lock sensor issues, but those were taken care of after 2010. I haven’t done much research on the newer models, but as a brand itself it’s been reliable. My dad owns an M45 and my brother owned a G35 sedan/coupe, FX35, and M37… no major issues.