sentences:  In 2010-12, the FIA GT1 World Championship acted as a senior series to this series.Drivers in GT1 drive were more experienced (and can be hired by the factory), drove more powerful cars, and the season was longer and visited more countries (including non-European countries).Because the GT1 Championship allowed performance balanced GT3 cars and 2009-spec GT2 cars in 2012, the only difference in the car lineups was the GT3 Championship still being restricted to GT3 cars.