Sharing CCTV footage of the suspects, the dealership said: "Two of the suspects first arrived and gained control of the night guard, tying him up and stripping him of his uniform at gunpoint.
"One of the suspects then put his uniform on and posed as the guard when armed response vehicles arrived for the alarm activation."
The dealership said the suspects gained entry to the showroom by cutting through the tin roof and used grinders to open the safes in order to access the cars' keys.
Captain Xoli Mbele said on Wednesday that Johannesburg Central detectives had arrested five suspects between the ages of 23 to 27 for business robbery.
The suspects are due to appear in court in Newlands on Wednesday.
The stolen vehicles have not yet been recovered. Investigations are continuing.