A lawyer for the victims' families suing Blackwater confirms the FBI gave her clients a deposit for the cars, which are now believed to be at the FBI lab in Quantico, Va.
Studying the cars is a key tool for the investigators, said former FBI agent Mike Rolince, now a CBS News consultant.
What does that allow an investigator to do?
"I think it allows the investigator to put the story together," he said. "And what you are hoping to do is match whatever rounds went into those vehicles back to weapons from which they were fired."
The FBI is also using computers to generate a virtual crime scene.
Three-dimensional reconstructions will help investigators determine the trajectory of the bullets as well as the speed and direction of the vehicles, providing crucial clues if Blackwater employees were acting in self-defense, as they claim.
"The better able you are to understand what happened then the more prepared you are to ask the right questions of people who were there," Rolince said.
The FBI team will put its findings together, and get them to federal prosecutors to determine what, if any, laws have been broken - and, more importantly, if there's enough evidence to bring any changes.