I have thought a little about the performance of the G37. Could the 3.7 been in response to the G37's heft? Or, could the 3.7 have given the engineers a license to "improve" the G which ultimately created heft?

I don't think a major acceleration performance increase was a goal of Infiniti. By increasing the power they could add stuff to the G - more luxury, more sound deadening, more "refinement", all of which added weight. With the added power they knew they could do this.

I am hoping Nissan's 370Z won't gain any weight - actually hope it loses weight, but I am very confident it will get heavier. Americans want more luxury, even in a Z...