http://www.edmunds.com/reviews/roadtests/firstdrive/45789/article.html

"While the sheer number of horsepower is mighty impressive on paper, and likewise scoots you along with alacrity, the 4.5-liter, 32-valve V8 doesn't feel like a 340-horsepower engine. A vehicle powered by 300 or more horses ought to possess a sense of heart-pounding action, but the Infiniti lacks the fervent pull that characterizes a high-output engine. While published numbers state that 0 to 60 acceleration times can be achieved in 5.9 seconds, we're looking forward to testing it ourselves (for instance, we couldn't duplicate the 6.1-second acceleration times noted in the Lexus LS 430's press kit; our road test editor could only eke out 6.4 seconds). A possible explanation for the Q's lack of "pin you to the seat" demeanor is its final gear ratio of 2.764, compared to the peppier-feeling Lexus' 3.266. Furthermore, transmission kickdown was sludgy when left in automatic mode (an automanual mode is available). We attributed this to a preproduction glitch and were assured by company representatives that the fuzzy logic, software-programmed system would be tweaked in the production models.