I went to an AutoX in the G35 on sunday.
It was a dam hot day.. almost 100 Degrees and 100% humidity
I ran 67-68s with VDC off and 70-74s with it on. I only ran two runs with VDC off, because my tires were at their tread warning level and I wanted to be able to drive home.
I could have made better times with it off 67s or less.
Semi stock Scooby Doos and Evos were running 65-68 with slicks they were running 64s
The fastest car of the day (a fully build 80s firebird racecar) ran a 59.
Here is the video.
http://www.youtube.com/watch?v=5Jy8voVvIwo