Perhaps Michael Bay is introducing the Stunticons in Transformers 4 as the latest reveal is what looks to be a darker take on Optimus Prime with the 2014 Argosy cab-over truck by Freightliner.
Michael Bay released the image on his site, which could very well be Motormaster.
The Stunticons also featured a number of sports cars, which we've seen revealed for Transformers 4 recently as well. Could they merge into Menasor?
Another possibility is Ultra Magnus.
Transformers 4 has a Summer 2014 release directed by Michael Bay and starring Mark Wahlberg, Jack Reynor, Nicola Peltz, Sophia Myles, Li Bingbing, T.J. Miller and Kelsey Grammar.