Bottle holders are on the inside of the doors.

CAUTION
Do not use the bottle holders for containers without caps. The contents may spill when the door is opened or closed.
Cup Holder
Storage CompartmentsMazda 6 Owners Manual: Gear Shift Indicator (GSI)
The Gear Shift Indicator (GSI) supports you to obtain optimum fuel economy and
smooth driving. It displays the selected gear position in the instrument cluster
as well as notifies the driver to change to the most suitable gear position corresponding
to the actual driving condition.
CAUTIO ...
Mazda 6 Owners Manual: Scheduled Maintenance (U.S.A., Canada, and Puerto Rico)
Follow Schedule 1 if the vehicle is operated mainly where none of the following
conditions (severe driving conditions) apply.
Repeated short-distance driving
Driving in dusty conditions
Driving with extended use of brakes
Driving in areas where salt or other corrosive materials are used
...