Kiara Moore was a week away from her third birthday when she was found in the silver Mini after police discovered it in the River Teifi in Cardigan, west Wales.
Officers had received a call about the missing Mini at 3.30pm on Monday and it was found just after 5pm.
Kiara was taken to University Hospital of Wales in Cardiff but did not survive.
On Monday afternoon, numerous Facebook posts claimed a silver Mini had been stolen from the town with a girl in it.
But the child’s father, Jet Moore, suggested his daughter’s death was an accident after the car had rolled into the river.
He wrote on Facebook: “She was an incredible happy young girl who lived I hope a great adventurous fun life.
“And may have done more than most people. Been skiing twice and skied her self! Paddled the great glen Scotland.
“Played on every beach we could. Had a Loving family and made us all happy.”
Explaining what happened, he said: “They got in the car to go home. Sat on bank card which snapped and needed money to get home etc.
“Went back to the office to get money from the desk and came back to no car. Looked in the river. No signs. So we thought she and the car had been taken.
“The police found the car a while later and went way beyond the call of duty jumping in and pulling her out.
“They tried to revive her for hours but unfortunately could not. Everyone done their best.”
Police added: “We’re investigating the circumstances surrounding this tragic incident.”
They appealed for witnesses who may have seen the silver Mini enter the river between 3.30pm and 4.50pm on the afternoon of Monday 19 March to call 101 quoting message 216 of 19/03/2018.