How can you choose to change the path or to stop developing the current car?
I might think it is only possible if you are the number 1 driver but i'm not sure.
Yes you have to be no. 1 driver in team. It think after 4th race or earlier they ask you wich way do you wanna go with development path. And after Monza they ask you in mails if you want to stop the development. I have platium already...
yes the trophy is glitched - for now.... but it will be fixed when patch comes out. Till then you can only do it in co-cop championship and outqualify your team mate 20x and then the trophy will pop up. Any difficulty doesnt change a thing