I'm Machine Enough
Beat the Panzerhund ride without killing anyone on "Bring 'em On!" difficulty or higher

So there are many ways to unlock this. Some people say you can actually kill as many enemies as you like if you are not on the Panzerhund's back when you do it. You can also ride through if you play on a lower difficulty (you need Bring 'em On! at least).

The achievement is missable, so if you don't have a save in that location, you'll need to load earlier spot and reach that part. It ends when you drop down into the water near the commander.

Since I played on I Am Death Incarnate difficulty, I couldn't be spotted if I wanted to survive, but that made it more fun for me. However, stealth isn't a requirement. If you are confident that you can make a run for it, you can be spotted at any point and the achievement will still unlock.

If you want to be sneaky, I recommend Constrictor Harness Contraption for the slow-mo and a silenced pistol to distract enemies with.