The Stig's primary functions on the show are to post lap times in various cars around the Top Gear Test Track in Dunsfold Park, and to train each week's guest in setting a lap time in the Star in a Reasonably-Priced Car feature on the show. In addition the Stig carries out other driving duties when the need arises.
The Stig has also appeared on some of Jeremy Clarkson's motoring specials, such as Heaven and Hell and The Good, The Bad, and The Ugly, as well as on BBC's Whizz Whizz Bang Bang.
The first Stig wore black overalls and helmet. It was introduced in the first episode of the current format by Jeremy Clarkson as the resident test driver, as the presenters could not consistently post fast times themselves. Clarkson noted that "we don't know its name, we really don't know its name, nobody knows its name, and we don't wanna know, cause it's a racing driver." Clarkson then described The Stig as having a very small brain, who had worthless opinions, and a disorder described by Clarkson as "Mansell Syndrome". Its job description was to "just go out there and drive fast".
Black Stig posted a lap time of 1:46 for the Star in a Reasonably-Priced Car segment. This Stig was used for the first two series of the show. It was then "killed off" at the start of the third series when he was shown driving a modified Jaguar XJ-S off the flight deck of HMS Invincible during a stunt and landing in the sea.
After the Black Stig was "killed off", a new "White Stig" was introduced, wearing white overalls and helmet. White Stig has been featured in the show beyond just the Power Lap segment. His work has included driving cars in other segments of the show, for example finding a winner between the Aston Martin V8 Vantage, BMW M6 and Porsche 911 Carrera S on the Isle of Man, and racing against the hosts in a bid to see who would cross the starting line at a race track; White Stig driving a Caterham Seven kit car from Caterham, Surrey to Knockhill racetrack in Scotland against the hosts in assembling an identical car from the ground up. In Series 10 The Stig was recruited to take public transport in the Cross London Challenge and had to deal with such tasks as riding a bus, using an Oyster Card and having to answer a mobile phone (but instead just stared at the ringing device).
White Stig has also appeared outside Top Gear in some of Clarkson's motoring specials, such as The Good, The Bad, The Ugly where Clarkson reviewed and compared American and non-American cars, Heaven and Hell, where the Stig was used to compare the track times of the Chevrolet Corvette C6 and the TVR Sagaris, and raced Clarkson, in a BMW M5, with a Ferrari F430. In Clarkson's latest DVD, Supercar Showdown, The Stig (in a Porsche 911) raced Sabine Schmitz (in an Audi R8) around the Ascari track in Spain to see which was the fastest.
White Stig posted the fastest lap time of 1:44.4 around the Top Gear test track for the Star in a Reasonably-Priced Car segment.
Marketing in the lead up to Top Gear Australia stated that the the cast would include The Stig's "Australian cousin but in the first episode he was introduced as The Stig.
Episode 3 of Series 9 was set in the United States, with the presenters purchasing American cars and driving them across four states whilst on holiday. One of the challenges set for the presenters was for the cars to set a lap time around a racetrack, for which "the Stig's American cousin" was introduced. He was nicknamed "Big Stig" by the presenters, due to being somewhat overweight.
Episode 4 of Series 10 featured the presenters driving across Botswana. To test the performance of the three cars used by the presenters around a dirt rally track, Clarkson introduced "The Stig's African cousin." This incarnation of The Stig was black, wore only Puma shoes, a loincloth and the iconic white helmet. He set lap times for two of the cars, but walked away from the track when Clarkson's Lancia Beta failed to start. The others joked that African Stig was trying to get a respectable time by walking the course, and didn't bother using the car as it was too slow.
The Stig's true identity is never revealed on the show, and in order to maintain the secrecy, all shots show him wearing full racing overalls and matching Simpson Diamondback helmet. All that can be seen from the gap between his helmet and jumpsuit is that he is a white male with dark hair. It is also known that he wears Size 10 racing boots as discovered by the Sunday Times and a well-timed camera flash managed to show The Stig's eyes by Auto Trader.
The identity of Black Stig was revealed to be Perry McCarthy when his book Flat Out, Flat Broke was published in 2003. McCarthy is a former Formula 1 driver and test driver for the Benetton, Arrows and Williams teams, and also tested for BMW F1.
The identity of White Stig has not been officially revealed. In a Winter Olympics special episode of Top Gear, The Stig was shown doing a ski jump using a snowmobile. According to the Swedish tabloid newspaper Aftonbladet, the driver performing the ski jump stunt was Dan Lang, a Swedish snowmobile cross driver. In January 2006, a Daily Express article reported that Julian Bailey was The Stig. The Stig has talked in an interview with a Dutch TV Channel, Veronica where he had a distinctly English accent. Both Darren Turner and Ben Collins have been linked to the role, with The Scotsman quoting Susie Stoddart as stating "OK, there are two Stigs. One is Ben Collins and the other is Darren Turner. How do I know? I'm a racing driver, nothing stays a secret for long in motorsport.
Collins has also been the subject of online speculation, although he has denied this, stating "those rumours are absolute nonsense" in the Western Daily Press newspaper. Collins was also referred to in the Health and Safety Executive report into the accident of Richard Hammond, named as a person "who worked closely with Top Gear as a high performance driver and consultant". However the report did not go so far as to name him as the Stig. In January of 2007 Auto Trader also commented on the possibility that Collins is The Stig, noting online speculation after "his appearance on Top Gear as part of a parachuting stunt", but also commenting that "(a)t 1.87m in height (over six feet) he could be too tall for the Stig’s racing suit." They quoted William Hill as offering odds of 8/1 against Collins being The Stig, with Russ Swift the 2/1 favourite. While Top Gear was filming in Zolder on 22 May 2008 doing a future segment, a camera crew shot footage claiming that they pictured The Stig as test driver Tim Schrick, though further evidence has refuted that claim, including Tim Schrick racing the Stig as part of the Germany vs England feature in Episode 6 of Series 11.
Both Russ Swift and Perry McCarthy have claimed that there is more than one driver who plays the role of The Stig.
The show has alluded to The Stig with Formula 1 drivers that visit the show. In the 26 June 2005 episode, Damon Hill appeared as the "Star in a Reasonably Priced Car". When asked directly by Clarkson if he was The Stig, Hill played on the fact that he may be The Stig, but then denied it. Mark Webber was interviewed on 31 July 2005 and at the conclusion of his lap, Clarkson presented him with an "I AM THE STIG" T-shirt.
When former F1 driver Nigel Mansell appeared on the show, Jeremy Clarkson noted that The Stig theorised that the Suzuki Liana (the show's "reasonably priced car" at the time) could achieve a 1:44 time on the track. Mansell proved the Stig's theory by lapping in a time of 1:44.6; The Stig subsequently posted a lap-time of 1:44.4 in the Liana. During the review of Jenson Button's lap, Clarkson commented that he, as did most of the other F1 drivers, took very different racing lines from The Stig's. Button commented that "...obviously, The Stig isn't a Formula One Driver, then", to which Clarkson replied, "might be.
Although The Stig does talk with celebrities while preparing them for their "Star in a Reasonably Priced Car" lap times, he is never shown talking on screen, and in Top Gear magazine articles he is portrayed as unable or unwilling to talk. Clarkson has written that The Stig is not permitted to talk on screen because any opinion he might voice on cars would be rubbish.