Additional tweets from Staci provides another image and a little background. Apparently the images were taken in Oklahoma as the driver was passing through on the way to a road show in Texas. Not sure what to make of the color change but it at least verifies that both characters are in the movie (as if there was any real doubt).
Update: Added picture of Ironhide from shalim with message "Check out these transformers trucks cruising on the 405. By the engraved Decepticon logo, it must be from the film." I believe he is referring to Interstate 405 (San Diego Freeway) in California and meant the Autobot logo. Link provided from the comments.