State of Decay: Year-One

Just my own experience. I've been playing this game for about 10 hours and have killed a couple 100 zombies with cars and have opened the car doors dozens of time with no luck on this achievement.

What just worked for me literally minutes ago was opening my door (Xbox Controller 'X') while driving in reverse, killed zombie and pop.

Maybe there was an issue with achievements when taking out the zombies while driving forward but I was getting numerous other achievements while playing too.

Again, this was my experience, hoping it helps somebody out.

This can be earned in less than 30 seconds. Just load up a new game of lifeline, sprint forward towards the truck, hop in and wait for a zombie to jump on the door and mash away (X).

bleep bloop.

Here is a video guide with English commentary for this achievement!

This achievement can be earned 10-15 minutes into the game when you have access to the car. When you start the car you'll have a horde of zombies run out of the garage to the right hand side of the car. The objective here is to try get a zombie to jump on the left hand side door then mash to kill it, once killed the achievement will pop.