Police stopped 30-year-old Michael McCluskey from Birmingham on the M5 in May, an hour after he had collided with a lorry near Gloucester.
The crash happened between junctions 12 and 11A on the M5.
McCluskey admitted to driving dangerously and failing to stop after an accident at Cheltenham Magistrates’ Court.
He is due to be sentenced at Gloucester Crown Court on 21 August.