The shot of an urban center being decimated by a blue energy beam is a strong turning point in the Man of Steel trailer, and Superman's inability to protect the city (presumably Metropolis) from such an attack has serious ramification for the plot. But those who've been keeping up on Man of Steel news and rumors know exactly what we're looking at.
Previously released tie-in toy commercials were suspected of spoiling General Zod's military force and weaponry ahead of the film, and these action scenes reflect those same powers possibly at work. The impact and surrounding cars being not incinerated, but lifted upward certainly provide what we'd expect from a 'Gravity Beam,' although Zod's greater goal is still a mystery.