I'm playing racing games since Gran Turismo 1, and I've been playing a LOT from GT3 to GT6, but now that I have moved to PC, I can say that Gran Turismo is really a few steps behind racing sims like Assetto Corsa.
Forza and Gran Turismo are usually called "simcade", so half way between sim and arcade. They are great games, but if you want a sim, you should check Assetto Corsa, Project CARS (going out in November), iRacing, or even the "old" RACE 07 if your computer is not powerfull enough !
GRID Autosport is a fun game, I've played ~25 hours in it, but it's not a sim either...
Our car is not in any of these games yet, sadly, but Assetto Corsa has announced that the GT86 will be added in a future update
As said before, keep in mind that you need a wheel to play racing games, with a pad you can learn the racing lines but you will miss a lot in term of feeling and steering angle management.
[ame="https://www.youtube.com/watch?v=voCYcSlXEqw"]Assetto Corsa vs Real Life | Mclaren MP4 12C GT3 @ Monza (Video & Audio) - YouTube[/ame]
[ame="https://www.youtube.com/watch?v=fTrwsokoNXg"]Project CARS Vs Real Life - Bac Mono @ Oulton Park - YouTube[/ame]