A user at Gran Turismo enthusiast site and forum GT Planet noticed the three best times in the race all used the same "shortcut." And by "shortcut" we mean the drivers completely bypassed two corners by driving straight over the grass as you'll see in the videos.
Players on the site are calling this an "Epic Fail" and complaining that "this will be the most ridiculous ruling if they let these kind of times stand. This isn't a rally stage..."
Eventually, the folks at SCEA threw out the times and reconfigured the course. But was that the right move?
Since the grounds were technically in play it's maybe not right to call the drivers "Cheaters" for finding the fastest way around (that's the point of a race). And even if they are cheating, as racing legend Smokey Yunick said "If you ain't cheating, you ain't trying." Except I think he may have actually said "'ya" instead of "you," "cheatin'" instead of "cheating," and "tryin'" instead of "trying," but whatever, close enough.