GT1 World Championship organiser SRO has announced that next year's revamped GT World series will now be based on GT3 cars, with current GT1 machinery pegged back to equalise performance.
The FIA's initial announcement of the changes to the championship for 2012 had suggested that measures would be taken to balance GT1, GT2 (GTE) and GT3 cars.
But the FIA and SRO boss Stephane Ratel have now agreed that GT3 will form the basis of the new regulations, with the GT3 cars uprated and - for 2012 only - present GT1 machinery restricted to allow equal racing. GT2/GTE cars will no longer feature.
"The meetings held over the past week have been extremely encouraging, and today we have a clear goal of what we can achieve in 2012," said Ratel.
"Using regulations adapted from the ultra-successful GT3 category is the correct way to go. It has been agreed with the teams and manufacturers that rather than bringing GT3 cars up to GT1 levels of performance, we will adopt a GT World level, to which the current GT1 cars will adhere, reducing development costs significantly.
"GT3 is the most successful GT category in the world and almost all of the major manufacturers are building cars to these specifications. This allows us to have a grid of 10 two-car teams, each representing a different model, while keeping costs under control.
"Using the FIA Balance of Performance, the current GT1 cars would be able to race with restrictions on their performance to bring them into line with the 2012 GT World specification. It has also been decided that GTE cars will not be eligible, as every manufacturer currently involved in GTE also makes a GT3 model.
"2012 will be a transition year, with the current GT1 cars able to compete alongside the new cars. In 2013, every car on the grid will be a GT World car, which will reflect the growing demand for GT3 cars in national and international motorsport around the world.
"In light of the current economic climate, this GT World specification is the correct solution to secure the future of the FIA GT1 World Championship."
Mercedes, BMW, Porsche, Ford, Audi, Lamborghini and Ferrari currently race in GT3, with the new McLaren MP4-12C also built for the category.
The initial 2012 GT World entry announced in July featured existing GT1 teams Young Driver, JRM, All-Inkl Munnich, Marc VDS, and Belgian Racing, plus GT3 squads Vita4one and WRT.