This for loop is not really needed, it is the same thing of doing :

var str2 = hacker2;

In the first big if statement, to check if they have the same name, you are only comparing the first letter of each name. To be sure your code also works if there names start with the same letter but have different names, you can write your code like that :

if (hacker1 === hacker2){
  console.log("What?! You both got the same name?");
} else if (names[0] === hacker1) {
    console.log("The driver's name goes first");
}  else  {
    console.log("Yo, the navigator goes first definitely");
}