Mazda 6 Service Manual: No.21 engine noise

No.20 fuel odor (in engine compartment)

No.22 vibration concerns (engine)

Other materials:

Mazda 6 Service Manual: Engine control system operation inspection
Main Relay Operation Inspection Verify that the main relay clicks when the ignition switch is turned to ON position and off. If there is no operation sound, inspect the following. - Main relay (See RELAY INSPECTION.) - Harness and connector between ignition switch and main relay termi ...

Mazda 6 Service Manual: Trunk Lid
WARNING Never allow a person to ride in the trunk: Allowing a person to ride in the trunk is dangerous. The person in the trunk could be seriously injured or killed during sudden braking or a collision. Do not drive with the trunk lid open: Exhaust gas in the cabin of a vehicle is dangerous. ...