Apollo missions/ Saturn rocket/ moon

I think the key word here is "vehicle", because that implies that it is carrying a person. In that case, yes, the Saturn V is the fastest vehicle because it had to break earth's gravity to go to the moon. Other rockets that have carried probes to the outer reaches of the solar system have probably been faster as other posters have mentioned, but I don't know if you would classify them as a "vehicle".

It is the most powerful.

ya its true