A lot of the time, for the power laps, when the car is rented privately, the person or a member of the party that owns the car will drive as 'The Stig' on its behalf. Makes sense really, for insurance issues and the fact someone familiarised with the car will get the best out of it. If you think of F1 drivers, if, say Alonso was to jump into Hamilton's car, with his settings, it would be an absolute mess. One 'Stig' wouldn't have time to get accustomed to the car. With incidents like today's episode and the 'interview' with the Sunday Times, it could be any member of the Top Gear staff. Still, that doesn't detract what an amazing character The Stig is. :P