GM vehicles medium-duty truck.

But General Motors took the edge off this weekend, releasing several images of its four Transformer vehicles. The Chevrolet Camaro is undoubtedly the über-Transformer, dubbed "Bumblebee," a major character in the saga of aliens who take mechanical forms when on earth. GM said it will "roll out a fully integrated marketing and promotional effort around the film in the near future, including a major Chevrolet promotion."

Insiders say this effort may include specially badged vehicles to commemorate the film, as well as the usual line of toys, posters and other movie-related accessories.

GM vehicles are not merely static displays in Transformers. They are clearly embedded in the story line. "Autobot Jazz" converts from a hardtop Pontiac Solstice. "Autobot Ratchet" is a Hummer H2 that has been modified to serve as a rescue vehicle. "Ironhide" changes from a GMC TopKick medium-duty truck.