May have been the Hotel's "VIP" limo. For that matter, the '58 Ghia Imperial may have been a de luxe airport limo for Michael, not his own ride. He may have had more modest tastes. For example: The car that Kay tries to go shopping in, and was stopped at the gate to the Tahoe compound, was a '57 Buick Special wagon (note the plain-Jane interior), a far cry from the higher end Roadmaster wagon. The rental car that Michael drove to Roth's house was a low-end '58 Ford Custom 500.
For this car buff, GFII is paradise for Fifties classics.
Ntra la porta tua lu sangu � sparsu, E nun me mporta si ce muoru accisu... E s'iddu muoru e vaju mparadisu Si nun ce truovo a ttia, mancu ce trasu.