There is a new F1 game (FIA licensed) coming out every year since many years now. Usually there is not much improvement. Over time they have gone with the latest standards in graphics, but thats about it.
Whats changing is mostly the driver names, the rules, new race tracks, liveries ect., to make it look like the F1 season that its named after. Mainly its a money making machine, that is aimed at F1 fans who always want the latest F1 feel, as they know it from TV.
But its good to hear you got yourself Project Cars 2. That gives a much more diverse experience, regarding tracks and cars, at a high realism level. I also like that you can drive every car on every track, without having to unlock things by winning challenges.
And you can drive at Bathurst as well... :)