The sledge hammers top speed is 255mph. I dont remember its other times though. 10s in the quarter. I dont know if it hit 255 with all the emissions stuff either... When car and driver put the McLaren up against the Ferrari Maranello Hennessy 96 650 hp NA lingenfelter ZR1 Vette and others.. it only hit like 214 or so. The vette beat it with the cats off. 216 or 217... I wish i still had that issue.
I do remember reading that the Mclaren clocked up way higher than the 214 it ran in Car and Driver though.