The driver of a milk tanker failed to stop after clipping a car and shunting it 100 yards along a dual carriageway, police in Wiltshire have said.
The accident happened on the A350 northbound between Chippenham and the M4, on Friday night.
Police said the car was spun around and pushed by the front of the tanker until it came to rest on the verge.
A spokesman said: "It was an appalling incident which could have caused injury or a fatality."
Anyone who witnessed the accident, or who may have seen the green tanker with a white cab, is urged to contact the police.