The G35 sedan Auto is Definately faster ten the 350z Auto.
I was riding in the backseat of the (2004)G35 with 4 other people and a 350Z Auto was following us to the game. Then we stopped at BK and on the way out the the Z and the G (ha that rhymes) were next to each other at the going onto I85 they both floored it an the G was on the outside lane, the Z came up quick and was 2 cars ahead but then the lane cut into one and there was a huge shoulder so we just flew by him on the shoulder and cut back in front, at 95mph we were even but at 120mph the Z was ahead by 1 car or so.

But we wer on the downhill so maybe thats why, but I would still love the Z's