Okay, the distance is 600 km. But if I have it right, (haven't been doing enough math lately thisisembarrassing....) For you to find out the displacement, you need to know the starting and ending points of the car trip.
The starting and ending points could be directional (S,W,N,E) or points (point X to point Y).
Say if you travelled 60 km to the north, your displacement is 60 km to the north. And if you travelled 70 but backtracked 10 km, your displacement would be 60 km to the north from where it started.
ireallyhopethisiscorrectsorry