Chevrolet 2010 HHR Owner's Manual page 141

Make sure the shift lever is fully in P (Park) before
starting the engine. The vehicle has an automatic
transmission shift lock control system. You have to fully
apply the regular brakes first and then press the shift
lever button before the vehicle can shift from P (Park)
when the ignition key is in ON/RUN. If the vehicle
cannot shift out of P (Park), ease pressure on the shift
lever and push the shift lever all the way into P (Park)
as you maintain brake application. Then press the shift
lever button and then move the shift lever into another
gear. See
.
Use this gear to back up.
To rock your vehicle back and forth to get out of snow,
ice, or sand without damaging the transmission, see
.
In this position, the engine does not
connect with the wheels. To restart the engine when the
vehicle is already moving, use N (Neutral) only. Also,
use N (Neutral) when the vehicle is being towed.
Shifting into a drive gear while the engine is
running at high speed is dangerous. Unless your
foot is firmly on the brake pedal, the vehicle could
move very rapidly. You could lose control and hit
people or objects. Do not shift into a drive gear
while the engine is running at high speed.
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