Board Thread:Metal Gear Solid V/@comment-3131736-20150621110740/@comment-4807396-20150621124539

Maybe it's unlocked a lot later than the other buddies and/or has to be developed at Mother Base at considerable cost?

From what I saw, almost all of D-Walker's functionality requires you to be piloting it, unlike all the other buddies. All we've seen it do on its own is mark enemies, and it has to be commanded to do that; contrast that with D-Dog, who can detect enemies and herbs without having to be prompted and can take other commands at the same time. Doesn't seem to be able to engage enemies independently of you the way Quiet can, either, and she can mark enemies too.

It may be silent, but it's not exactly invisible. I'd imagine it stands out more even in wheel mode than Snake ever does on foot; you wouldn't be able to move around with it in plain sight of enemies as is possible with D.Horse (by hanging over the side of the saddle). You can only use D-Walker's mounted weapons while piloting it, and all the mounted weapons we've seen in action so far were lethal. The only non-lethal option it has is only viable at extremely close range; good thing D-Walker is fast. Thus, it's usefulness in S-rank runs is debatable.

It stands up to small arms fire pretty well, from what I saw, but a frag grenade made it stumble over, and that APC's cannon scrapped it pretty quickly once it got a bead. Who knows what the repair costs are like for it at this point?

I'm speculating quite a bit, I'll admit, but I'm not seeing a superweapon in D-Walker.