Little Logan Padden was strapped in to his car seat and escaped with a minor facial injury in the accident which killed his parents Tom Padden, 20, and Louise Evans, 23. The car's driver, Logan's grandfather Stephen Padden, 56, was also killed.
The three adult passengers who died were not wearing seat-belts when Stephen dozed off at the wheel and careered the Peugeot 406 into a crash barrier as the family returned from a holiday.
Suzanne Padden, 51, Stephen's wife and Logan's granny was wearing her seat-belt and survived.
The family were driving from Gatwick to Porthcawl, Bridgend, after a holiday in Morocco.
Mrs Padden said she was concerned her husband had a sleep disorder, saying "I asked Stephen if he wanted me to drive but he said he was fine," she said. "I fell asleep and the next thing I remember was the car rolling and loud bangs."
All three victims were thrown out of the car just 10 miles from home.
Cardiff coroner Mary Hassell recorded three verdicts of accidental death.