In many ways, The Stig is like Santa Claus. So is this driver doing insane donuts in a modified London Taxi Cab as part of the Top Gear Festival 2011 really THE Stig or a similarly skilled driver in Stig clothing? Do we care? The spirit is in him.
Also, as far as we can tell, that isn't someone dressed as Tiff Needell, that's actually Tiff Needell.