The "Rig Stig" is one of The Stig's many cousins, and was featured in Series 12, Episode 1. Like many of The Stig's cousins, its appearance was quite short, only to display the episode's first challenge.
S12E1 saw the 5,000-pound Lorry Challenge, with the first event being to powerslide a lorry. To prove this was possible, the presenters were introduced to "The Stig's Lorry-Driving Cousin," stating that its favorite all-time tune being "Forever Autumn" by Justin Heywood and that it owned the world's largest collection of pornographical material. This cousin, quickly nicknamed the "Rig Stig" then drove up in its vehicle blasting music from the band ACDC. Stepping down out of the rig, a racing-modified MAN truck, Jeremy remarked that it was as fat as American Stig, but with a sunburn on its whole right arm.
The Rig Stig then proceeded to perform an impressive powerslide around a skid pad, utterly shredding the rig's tires and sending the presenters running for cover. The display inspired premature confidence in Jeremy, James, and Richard; not only were they entirely unable to perform a powerslide, Jeremy accidentally got the gear lever jumped up his butt and lost his suspension link while Richard ran over and destroyed his dog-house hood ornament.
It could be argued that the lorry powerslide challenge was a farce: The Rig Stig was using a properly-tuned vehicle, while the presenters were just driving stock lorries with aesthetic modifications.