The 2011 International Superstars Series season will begin at Monza in Italy this weekend (9-10 April), as the touring car series continues to grow in size and popularity.

Nine car marques will be represented at the season opener. These will be led by BMW, with reigning champion Thomas Biagi lining up again for BMW Team Italia, run by the ROAL Motorsport squad. Stefano Gabellini remains with the team for 2011, while 18-year-old rookie Alberto Cerqui replaces former champion Gianni Morbidelli in the lineup. Cerqui has impressed in pre-season testing after stepping up from Formula 3.

Reigning champion Thomas Biagi returns with BMW Team Italia for his title defence

Another well-known team fielding BMWs are Campos Racing. The Spanish outfit joins the series for the first time, with World Touring Car Independent Champion Sergio Hernandez being partnered by Spanish-Turkish driver Isaac Tutumlu.

Movisport field four BMWs for Francesco Ascani, Sandro Bettini, Alex De Giacomi and female newcomer Francesca Linossi, with former single-seater and GT ace Christian Montanari and former ski champion Kristian Ghedina lining up in together  in BMWs for RGA Sportsmanship.

Audi Sport Italia will field three Audi RS4s for Ermanno Dionisio, Roberto Papini and Ricardo Bossi, while two Chevrolet Lumina CR-8s will be entered by Motorzone Race Car for Fabrizio Armetta and Italian-Russian rookie Alessandro Kouzkin, who was backed into the series by Chevrolet Motorsport Europe boss Eric Neve.

Mercedes were BMW's nearest rival for most of 2010, and are once again represented by the Romeo Ferraris and CAAL Racing teams. Johnny Herbert leads a four-car entry from the former, which also features former champion Max Pigoli, rookie Andrea Dromedari and female racer Michela Cerruti. Luigi Ferrara returns for CAAL after finishing third in 2010 and is joined by Riccardo Romagnoli. Nico Caldarola has formed the new Roma Racing Team which will also use Mercedes – driven by Caldarola himself and former FIA GT champion Matteo Bobbi, who makes his Superstars bow at Monza.

Former champion Max Pigoli and Johnny Herbert will lead Mercedes' 2011 contingent

Lexus are represented on the Superstars grid for the first time, with a sole entry for Diego Romanini under the MN Motorsport banner, run by MRT by Nocentini, who will also enter a single Chrysler 300C for Mauro Cesari.

A single Cadillac CTS-V is entered by RC Motorsport for Roberto Benedetti, while Swiss Team returns with its Maserati Quattroporte which will be driven by Andrea Chiesa, and perhaps later in the season by multiple GT champion Andrea Bertolini who has been developing the car. Ferlito Motors lineup with a pair of Jaguar XFs for Luigi Checchi and Francesco Sini.

Maserati - with the stunning Quattroporte - Cadillac, Jaguar, Audi and Chrysler will be joined by series newcomer Lexus on the grid

An expanded TV plan will see the Superstars Series broadcast live in 36 countries this season, with Motors TV showing the Monza races live in the UK at 10:30 and 15:30 BST.