Starting today it looks like filming of Transformers 4 has moved from Pfugerville, Texas to Taylor, Texas. What exactly is being filmed is unknown but spotted on the set was Mark Wahlberg, Michael Bay, and Rusted Optimus Prime. Images from the set can be found here and here.

As for the two images below, they were taken by @NickForrester on Monday as the location was prepped. Now my guess is the location is supposed to invoke the small town American ideal visually (you know kids with kites or playing baseball, 50s era cars, etc.) and I suspect the red fire truck is part of that. It could be an alt mode to a Transformer, I just doubt it.