Upshifting
For normal acceleration, Mazda recommends these shift points:

For cruising, Mazda recommends these shift points:

Downshifting
When you must slow down in heavy traffic or on a steep upgrade
, downshift before the engine starts to overwork. This reduces the chance of stalling and gives better acceleration when you need more speed. On a steep downgrade
, downshifting helps maintain safe speed and prolongs brake life.
Gear Shift Indicator (GSI)Mazda 6 Owners Manual: Mazda Radar Cruise Control (MRCC) (Some models)
The Mazda Radar Cruise Control (MRCC) system is designed to maintain headway
control*1 according to the vehicle speed using a radar sensor (front) to detect
the distance to a vehicle ahead, and by presetting the vehicle speed between 30
km/h (19 mph) and 145 km/h (90 mph), the driver is freed ...
Mazda 6 Owners Manual: No. 1 one or more on-board diagnostic functions inoperative
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while doing the inspection to discover whether
poor contact points are the cause of any intermittent malfunctions. If there
is a problem, check to make sure connectors, terminals and wir ...