videos :

YouTube - Transformer 3 Filming Action Scene Live Stunt Whiting, Indiana - Cline Ave.
YouTube - Transformer 3 Filming.. Aftermath of stunt. Whiting, Indiana Cline Ave (truck is at the end of the video)

maybe it's just Optimus but his truck doesn't look like this truck

 

wow, what a bizarre sight. Looks a bit of a different shape to Optimus too.

 

definitely a CGI Reference Action Plate for either the Spike-Semi in a similar style to Bonecrusher in the freeway fight from "TF" OR for the Decepticons trying to stop Optimus from getting somewhere.

maybe even an Entrance Plate for someone other than the Spike-Semi or Optimus

 

Dont think its optimus. His alt mode is completely different. The sleeper cab isnt the right shape to be optimus, and the wheelbase is too short.
Not sure how accurate a referance truck would have to look though, as many of those details can be added/taken out with cgi.
Either way: YAY AWESOME HIGHWAY CHASE! ROTF lacked any good chases.
I highly doubt its prime though as he wouldnt just smash into human-driven cars like that, so it has to be a 'con.

 

That is weird.... it's neither Prime or the Spike truck... so are we having a 3rd truck character in the movie or is the Spike truck going to go through a couple of alt modes?

 

Ultra magnus?

 

Sweet! I believe there are other blue stuff in the background too.

 

Whats this "spike truck" i keep hearing about?

 

Interesting to see that. I remember a while back someone posted a photo on this site from the set of a blue (actual blue, not for cgi) truck (with trailer). I wonder if this has anything to do with that?

edit: Just seen one of those videos..there was that tall bluescreen truck but also at the beginning you see a long-nose (Magnus?) with a blue paint-job..

 

I'm beginning to wonder if the Nascars really are Stunticons and this bluescreen truck will be Motormaster.

Just something to think about.

And yes I know Nelson said that the Nascars aren't Stunticons, but I don't trust the guy.

 

Very odd, indeed. Magnus has been a rumored character for a while now, so maybe this is him?

 

Whoever the blue truck is... they will be transforming during this sequence. Like Optimus did in TF1 with Bonecrusher. Awesome!

 

Ultra magnus ftw!!!!!

 

i want me some ULTRA MAGNUS

 

Yay, Ultra Magnus! :3

 

Maybe it is Motormaster. I know they said no Stunticons, but hey, maybe he is a stand alone.

 

Ultra Magnus!!!!

 

I'm just sayin, how do we know it's TF3 set?

 

If it is Ultra Magnus, they better give him a robot mode that looks like his G1 self like the way they have Optimus.