The four injured, one of them a young woman, were among more than 20 young racers using a bridge across the Chao Phraya River in Phra Nakhon Si Ayutthaya district about 2am.
They were hit by pickup carrying two men.
Jirayu Boonsatit, 28, the pickup driver, told police he and his friend were heading home after a night out drinking. He said he intentionally hit the teen racer because he was displeased with the way they were tearing up quiet streets at night and harassing people, according to police.
Mr Jirayu allegedly admitted deliberately driving into the riders who were at the back of the group.
After the crash, Mr Jirayu and his friend, who also sustained minor injuries, did not flee the scene because they were too drunk to go on, police said.
The two men and the teenage racers would be charged with violating a curfew order, in addition to other basic charges, police said.