iRacing version is a GT3 racing car, those are all 12c road cars.
Simraceway has the 12c road car though, along with a laser scanned Silverstone.. Would be nice to have seen that in the comparison, the Simraceway 12c has decent physics and sounds, but poor graphics due to the dated graphical engine (lighting/shadows especially), even though they use high res textures and a lot of work clearly goes into making the content look as good as possible.