The Subaru Impreza 2.5 WRX may have once been the fastest 4 door sedan in the world, although there is some debate on that subject. The Impreza’s record was recently broken by the Cadillac CTS-V. Whether the record was valid is not clear for two reasons. Whether it qualifies as a sedan is debatable, for one thing. The fact that it may have technically been considered a prototype at the time that the record was set is the other problem with the claim. One thing is undeniable, though. The Impreza 2.5 WRX is indisputably the world’s fastest Subaru thus far.