A woman got out of the car to help him when the 18-year-old allegedly got behind the wheel and drove the car into a crowd of people, including a pregnant woman who suffered a suspected broken leg.
Another woman suffered a broken foot and a man suffered "a multitude" of minor injuries.
The woman who was originally driving has also been charged with drink driving.
Detective Sergeant Will Loughrin of Hamilton CIB said a total of six people were taken to Waikato Hospital by ambulance.
The young man who got out of the car to be sick had a number of teeth broken in the incident, he said.
Police are appealing for any witnesses not already spoken to by police to contact them on (07) 858 6200.
Inquiries are continuing.