As per Remco Towing Products website:
2005 Mazda 6 ALL FWD I4 2.3L cyl 5-Speed Manual Manual
Notes
•Towable as is without speed or distance restrictions. See Owner's Manual for confirmation and procedures.
•No Base Plate available from Blue Ox for this vehicle. May be Custom Application.
•No formal testing has been done by Remco on either the 5-Speed or 6-speed Manual Transmissions versions of these vehicles. Remco has not heard of any problems arising while towing these vehicles. Please check your Owner's Manual for confirmation and towing procedures if available.