This achievement may seem like one of the worst to get in game (for now) but don't worry because I have found easy (and most important) fast way to obtain it!

What do you need:

• Any vehicle (even starter cars will work!)
  
• Complete Incommunicado map to obtain harvester + forwarder (or you can just buy wooden logs, it's up to you)

Step 1:

Go to this spot, you should see bunch of rocks on the way, they're going to stop AI cars which is not good

(marked spot with cursor btw)



Step 2:

Build wooden bridge above those rocks so the vehicles can drive without problems



If you're using forwarder then here is extra step:

(if you're buying logs then just deliver them to construction zone and ur done)

You can cut some trees from nearby forest, for example i had to cut 4 for my bridge but it might be 3 or 2 if you know how to place bridges (i suck at it)

Step 3:

Make sure that you clear trash out of the way where AI cars spawn. they're gonna get stuck on them if you don't





Step 4:

Stop at this place, turn on handbreak and wait for cars to drive by



Step 5:

If AI pass you then start to follow it, when car can't drive up mountain or get stuck in mud just push it!

Step 6:

DON'T leave AI car on it's own, even after 1.5 update they can't drive very good on mud

Extra:

If you wonder, here is how my path for cars looks like:

I hope this guide can save someone from suffering and will teach you how to handle AI on extreme road such as this leading to Lantevken castle. Oh yeah and don't forget to grab 40k barrel and crane toy from castle while you're at it!

Here is proof of me getting achievement (i was using scout Invictus Type A from dlc for screenshot)