The baby girl, named Vasile, was travelling in the car along with her mother and another woman when it collided with a truck on Tuesday.
The accident happened at around 9am on the CM-4000 motorway near the town of Cebolla in the province of Toledo, central Spain.
Vasile was born just six and a half kilometres away, on the same stretch of road, on March 13th, when her mother, Victoria Samiri, 40, gave birth in the car at the side of the road while on her way to Talavera de la Reina hospital with her husband.
On Tuesday, Vasile was on her way back home after some routine vaccinations, along with her mother and another woman, when their car collided with a truck at a crossing.
The crossing is notoriously dangerous and there have been several accidents at the same spot in the past, some of them mortal, the mayor of the family's hometown of Malpica de Tajo, Juan Carlos Flores, told Spanish daily ABC.
"We are so sorry. The little girl was born and died on the same spot," said Flores, adding that the town would observe two official days of mourning.
The car rolled onto the embankment and firefighters spent around an hour freeing the baby and the two women.
The body of the baby was recovered, while her mother was airlifted to hospital and is currently in a "serious condition" according to police sources.
The other woman, who was driving the vehicle, was also taken to hospital by ambulance. She is currently being treated in Nuestra Señora del Prado de Talavera de la Reina, the same hospital where, 16 days ago, doctors cut Vasile's umbilical cord.
The baby was thrown into the boot of the car upon impact and police are currently investigating whether there was a failure in the mechanism of her car seat.