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£ Lorry Challenge", with the first event being to powerslide one. 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 Stig, quickly nicknamed the "Rig Stig" then drove up in a racing-modified MAN truck blasting "Highway to Hell" by ACDC. As it stepped down out of the rig, Clarkson remarked that it was as fat as American Stig, but with a driver's sunburn on its whole right arm.
Rig Stig then proceeded to perform an impressive powerslide around a skid pad, as well as donuts, utterly shredding the rig's tires and sending the presenters running for cover. The confidence inspired by this display turned out to be premature; not only were the presenters entirely unable to perform a powerslide in their lorries, Jeremy accidentally got a gear lever jammed up his bottom and lost his suspension link while Richard ran over and destroyed his dog kennel "bonnet".
It could be argued that the lorry powerslide challenge was a farce: The Rig Stig was using a properly-tuned racing vehicle, while the presenters were just driving stock lorries with aesthetic modifications.