LOL, that the game would give you full tuning after chapter 21 is just wishful thinking. I am chapter 75 and still the car isnt maxed out. I wonder if yet another tuning bar appears when I have completed chapter 80. And yeah, the only way to change the tune is to play time attack and select another tune. But time attack is kinda useless when your car isnt maxed out so playing that mode is pointless. But to be honest I dont really care, someone will probably come up with a car editor or share a a folder with all the car profiles maxed out.
What I do care about is that someone fixes so Multiplayer LAN works. Right now all 4 setups gets detected, and it shows 1p,2p,3p≈4p available and you can choose accept challengers after selecting your car, but even if you start player 2,3 or 4 it dosent detect that player 1 is currently playing and accepts challengers so you wount get the YES / NO to challenge player 1, it just gives you the same option to accept challengers or not =(