Xymphora has a good summary of the story with references and analysis.

Amazingly, (see the last line of the article) the Americans are (or were) saying that they did not know the whereabouts of the car which they shot up.

When The Associated Press in Baghdad asked the U.S. military to see the vehicle on Saturday, the military said it didn't know where it was.

See also:
http://www.ilmanifesto.it/pag/sgrena/en/.