MichaelBay.com has revealed another vehicle being used in Transformers 4, "The Ultimate Sonic RS, just pure fun. High resolution: http://bayhem.com/13XdH30". The picture and that description is all that was posted so unknown if this is a Transformers alt mode or a car one of the human characters drive. Still, much more fun to just assume its a Transformer and then try to guess the character. Post your guesses in the comments.