Or even in the SmarT Start Guide:
ACCELERATED WARM-UP SYSTEM (AWS)
Vehicle Starting:
Your vehicle is equipped with SKYACTIV combustion technology. This
technology includes AWS (Accelerated Warm-up System) for optimal
emission performance during cold starting conditions.
Cold Start (e.g., First start of the day on cold mornings):
Depress the brake (Automatic Trans.) or clutch (Manual Trans.), when the
key indicator light turns green push the START/STOP button.
What you will notice: On start-up, the engine speed and sound are
higher (1500 RPM) for 30 seconds to 1 minute to quickly bring the catalyst
to efficient operating temperature. The RPM will reduce to idle once the
temperature is achieved. This is normal engine operation under cold
start conditions.
Time to read the manual!