Lexus 2004 GX470 Owner's Manual page 69

GAUGES, METERS AND SERVICE REMINDER INDICATORS
TACHOMETER
NOTICE
Do not let the indicator needle get into the red zone. This
may cause severe engine damage.
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The tachometer indicates engine speed in thousands of
rpm (revolutions per minute). Use it while driving to
prevent engine over-revving.
Driving with the engine running too fast causes excessive
engine wear and poor fuel economy. Remember, in most
cases the slower the engine speed, the greater the fuel
economy.
It is not a malfunction even if the needle of the tachometer
returns to the bottom position when the ignition switch is turned
to the "START" position.