No person shall unnecessarily race the motor of any vehicle and no person shall operate any motor vehicle, except in an emergency, in such a manner that the vehicle is so rapidly accelerated or started from a stopped position that the exhaust system emits a loud, cracking or chattering noise unusual to its normal operation, or whereby the tires of such vehicle squeal or leave tire marks on the roadway, commonly called "peeling". That the foot of the operator slipped on the accelerator is not a valid defense to a violation of this section.