So I finished all of the championships and I’m here to confirm that there is no ‘‘GRAND PRIZE’’ if anyone is wondering, you get an achievement and thats about it 
anyways so to that it was also my last achievement for the game, yes I have 1000 Gamerscored the game and have all the cars already, it was faster than I expected but was fun overall, looking forward to Turn10/PlaygroundGames for them to add more Chievos 
Well done!
I’m 4 championships away from the first finale … way behind you champ
While I’ve certainly logged enough hours on the game to do that, I’ve only completed 2, maybe 3 series since the 2nd finale. I spend 99% of my game time online.
No Grand prize "(
Could have told you that weeks ago; some people have 1000G on both consoles as well.
They did add new Rivals today; at least something to keep us busy 
yup
currently I’m trying to post a fast lap time on every track/PI leaderboard I can, just gonna try to be in the top 500 and of course the top of my friends list, only person that I can never beat is Prime Barricade, hes hard to beat xD