What is the fastest tuned car in forza motorsport 4 game

from my experience, its a toss up between the veyron ss, Hennessy venom gt, and the agera, all dlc but out of the 3, in a straight line the agera and venom can out run the veyron to top end due to weight, the veyron however can launch do to awd.. if u dont have the dlc, it would probably be the Zonda, or the Bugatti veyron 16.4