The night before leaving an SUV containing a homemade bomb in Times Square, terrorist Faisal Shahzad did a dry run for his fiendish plot and dropped off a getaway car nearby.

But the "idiot" bomber was unable to use that vehicle -- a white Isuzu -- because he had accidentally left the keys behind in the smoldering 1993 Nissan Pathfinder after parking it on West 45th Street with the bomb, a law-enforcement source said.

Shahzad instead was forced to take a Metro-North train home to Connecticut that night.

Shahzad (30) has told investigators he drove the Isuzu to New York City on Friday night and went through Times Square past the location where he would drop off the Pathfinder the next night, the source said.

u00a0