At the bridge on State Highway 26 in Te Aroha, the driver - believed to be Keenan - abandoned the vehicle and jumped into the Waihou River.
"Despite a prolonged search by police along the banks of the river, the driver was not located."
Police had since spoken with Keenan's family, who maintained they had not had contact with him since Sunday evening.
"Cody does have a history of actively evading police, but we are obviously concerned for his welfare, given the river levels were higher than usual due to the heavy rain over the weekend.
"We would therefore like to hear from anyone who has seen Cody since Sunday night, so that we can provide some assurance to his family that he is safe."
If anyone has seen Keenan, please call 111, or contact Crimestoppers anonymously on 0800 555 111.