Nick Ginetta's customers at Nations Trucks in Sanford each receive a $400 (250) voucher that can be exchanged at a local gun shop for the assault rifle, or any other firearm of their choice, when they buy a vehicle.
Mr Ginetta, the dealership's general sales manager, said: "AK-47s have a reputation in people's minds. So, I came up with that to be a little controversial, to cause a little buzz."
He said that the stunt - which he claims he dreamt up to salute America's servicemen and women - had brought in more buyers than when he offered free TVs, petrol for a year or cruises to the Bahamas.
Brian Tooley, chief of Sanford's police department, said he had no objection to the promotion because buyers must still pass background checks and meet Florida state guidelines before they can get a gun.
But critics claim that the promotion will put more weapons on the streets of a state where gun crime is prevalent.
"They've got no business giving those rifles away," said one Vietnam veteran at a welfare hall nearby.