Now you are thinking this character is Inferno, the fire truck from G1 cartoon but Nelson has already rejected that theory, "And it's not Inferno, Hot Spot, or Pyro. You'll see." He further teased, "I think fandom will faint when they find out who this fire truck is. It's going to be like when people saw Optimus Prime for the first time--with flames. I really hope they don't reveal the name until the movie premieres." The current fan favorite theory seems to be Ultra Magnus.
Also below is a video with some time lapse, behind the scenes footage, NEST troops in action, and explosions including a new angle on the bus explosion as TF3 production worked at State and Wacker this weekend. If that isn't enough boom, the last video is more footage from filming at Hotel 71 from last week. Thanks to Ray and Greg for the links.
Update: Added note about type of fire truck from the comments.