Weird baking up noice help!!!!

[DOOMMONKEY777]

ok for the record i got my 370z at 119 miles the dealer sad he had to deliver the car here and it took some mileage it is a base w/ sport pkg. 2010. here's the thing i have about 550 mi on it total i have been driving it normally in some occasions just give it a lil kick, never floored it and don't mess around, just driving 4 now at least until i brake it in. But recently i started hearing this very loud noise from underneath my car like metal grinding.......ummm when you run out of brake pads on ur car and u hit the pedal it goes kkkeeeeeeee ..yee that one well i get that when am backing up can any1 explain??? plz ???