Mazda 2008 Mazda3 4-Door Owner's Manual page 129

Driving Your Mazda
Starting and Driving
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.
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