In the briefing scene in the beginning where stronger throws out the deck of cards, he says less than a dozen "decepticons" are in hiding, meaning autobots. That means that at that time, only 11 cybertronians were alive (that they knew of).this included: optimus bumblebee ratchet hound drift crosshairs and leadfoot. Who do you think the possible other four were? I doubt it was all the other autobots from Chicago, because there were probably other bot casualties other than ratchet and leadfoot.
I really think Dino/mirage was killed offscreen, as he probably would of taken leadfoots place in the film but Ferrari said no killing their car again, and they replaced one red bot( Dino) for another (leadfoot). Leadfoot was probably killed off cuz his voice was so similar to crosshairs