1)open the game

2)sit in the main menu

that's it now just wait until you get all of them, you can minimize the game if you want and do other things while you wait

just know, don't get in the game and start driving because it won't load any achievements, just wait in the main menu


P.S. took me 0.7 hours to get all of them and it should take you even less if you just sit in the main menu and not play at all