Some say he built his own delorean time machine to travel back in time in, but his travels back in time if he beats his fastest lap time on top gear of 1:15.1 seconds. And some also say he has to beat it in the delorean.
Some say the reason he will not take his helmet off is that he is really an alien from an advanced planet far far away and that seeing these aliens will cause you to shrink like Richard Hammond did when he saw him.
Some say he has a 'Made in China' tag behind his neck.. All we know is he's called The Stig