The Triple 8-run works Vauxhall effort continued with a trio of entries in their second season with the Astra Sport Hatch.
Vauxhall's only opposition for a sixth straight Manufacturers title came from SEAT, who replaced its trio of Toledos with a pair of new Leons.
Scottish driver Gordon Shedden graduated from the SEAT Cupra championship to replace Dan Eaves, while Gareth Howell again appeared in a third car later in the season as he had in 2005.
Synchro Motorsport ran James Kaye in their Honda Civic Type-R for a fourth straight season, while Jason Hughes also returned driving an ex-works MG ZS for his Kartworld Racing team.
Running bio-ethanol fuel for a second year were Tech-Speed Motorsport, who once again ran Fiona Leggate in their Vauxhall Astra Coupe.
Mark Proctor switched from his Astra Coupe for his second season, his Fast-Tec Motorsport team instead running the Honda Civic Type-R driven by Tom Chilton in 2005.