Amazing work. Simply beautiful. I really can't fathom how you manage such detail, especially at that scale! How long have you been working on this one? Can we see him next to your Bumblebee? I'm really knocked out by this one! One nit pick though- that's not a COE (Cab Over Engine) truck. G1 Prime was a COE. Your's looks like it's based on Laserrod Prime/ RID Scourge. (Which happens to be a favorite of mine!)
It looks great, but my only nitpick would be the trailer's position. It needs to sit further up, since the fifth wheel on a semi would be (traditionally) in between the duals... It looks 'off' because there's too much space between the semi's cab & trailer...
Mmm... the face plate is sculpted using epoxy putty, the rest is an amalgam of putty and polyetilene -sheets- folded-n-cuted. Everything is glued, and i use some car primer for the ultimate surface covering.