The car is one of four Maseratis taking part in this weekend's first round of the FIA GT1 World Championship at Yas Marina, Abu Dhabi. Bartels/Bertolini clocked 2:08.714, a time beaten only by Mutsch/Grosjean's Ford GT.
Miguel Ramos, together with a newcomer to Maserati as well as ex-Formula 1 driver, Enrique Bernoldi, also had a positive session in which they improved throughout.
Another crew who took top marks was Altfrid Heger and Alex Margaritis who closed out in seventh after holding second for a lot of the free practice session.
Italian driver Bobbi (confirmed as a Vitaphone driver after last year's fine performances) and Belgian, Longin, (from Corvette) finished in ninth.
The drivers will have felt the heat and humidity in Abu Dhabi as temperatures inside the cockpit reached almost 60°C.