No person shall permit a motor vehicle to stand unattended without first stopping the engine, locking the ignition, removing the key from the ignition and effectively setting the brake, air temperatures permitting, and, when the vehicle is standing upon a grade, turning the front of the front wheels toward the curb or side of the highway. This section does not apply to authorized emergency vehicles. (Added 1971, No. 258 (Adj. Sess.), § 3, eff. March 1, 1973.)