This game is officially called an "action racer". Kind of a middle ground between arcade and simulation. Cars still handle a bit like Forza 4, but with a bit more grip. It's definitely not an arcade game. Go ahead and put your AI settings on "insane" and see what happens, lol.
It's a totally different game from Forza Motorsport, its a side project. There will still be Forza Motorsport 5. Also it's not as simple as copying and pasting the cars from Forza 4 either.