This is a Maya 5 file.
Smooth Proxy is used with low res mesh in 1 layer for animation and high res mesh in another for rendering.
All hydraulic pistons are fully working using aim constraints.
Set driven keys are used for shoulder and elbow rotation.
Hands are also controlled via sdk and fingers are setup with curl and spread attributes.
Cables for the neck and shoulders are easily animated and are setup using either joints with parented ik or curves with blendshapes.
A metallic shader is included which looks good when rendered with mental ray while procedural textures are used for the cables.
Figures for the low res mesh are
84585 polys
84237 verts