The 15-year-old boy was walking on Old Taupiri Rd near Ngāruawāhia about 5pm on Wednesday when he was struck by a car and run over more than once, Detective Inspector Darrell Harpur said.
The boy remains in Waikato Hospital in a critical condition.
On Friday, Harpur told RNZ the boy had "multiple fractures and breaks, internal injuries, surgeries... he's going to be in there for months".
He described it as a "particularly nasty incident".
A Waikato man has been charged with wounding with intent to cause grievous bodily harm and was to appear in the Hamilton District Court today.
Further arrests were not being ruled out.
The car believed to have been used was found by police on Thursday abandoned in the carpark area of the Pukemokemoke Bush Reserve near Tauhei.
Police want to hear from anyone who may have seen a black Toyota Auris, registration number NBE817, or who has dashcam footage, who were travelling in the Huntly area on Great South Rd and the Taupiri area on Wednesday particularly between 4.30 and 5.30pm.
They also want to speak to anyone who saw the car or may have dashcam footage in and around Pukemokemoke Bush Reserve on Tauhei Rd.
