Oliver Nicholls struck Isla Cochrane while driving on Oakington Road last September.
The 22-year-old from Godmanchester had overtaken a vehicle turning left into New Road, towards Histon, and had misjudged the road.
He mounted a pavement and struck 14-year-old Isla Cochrane.
A forensic collision investigation report revealed Nicholls had reached speeds of up to 71mph moments before the fatal collision, despite the speed limit being 40mph.
Nicholls stopped and he and a passenger, who were uninjured, got out of the car and called for an ambulance.
Paramedics rushed Isla, of Lawrence Close, Girton, to Addenbrooke’s Hospital in Cambridge, but she died of her injuries during the early hours of the following day.
DC Kim Marshall, Cambridgeshire Police:
"Nicholls’ reckless driving that evening led to the death of a young girl, which has devastated her family and friends.
"There is nothing that highlights the danger and devastation speeding causes more than a heart-breaking case like this one.
"Our thoughts remain with Isla’s family and I hope the sentence handed to Nicholls will provide some form of closure for them.
"I would like to pay tribute to their bravery throughout the course of this investigation."
Nicholls told investigators that when he overtook the car waiting to turn left into New Road, he thought he was travelling at about 40mph and had mistaken the cat’s eyes on the cycle path as being the middle of the road.
Isla, who had been wearing a helmet, had her cycle lights switched on but, despite this, Nicholls said he did not see her and knew something was wrong when he hit the kerb and braked hard, but it was too late.
On 19 December 2023, Nicholls was sentenced to four years and 10 months in prison at Cambridge Crown Court after pleading guilty to causing death by dangerous driving at a hearing last month.
He was also disqualified from driving for five years and must pass an extended test before he could get a licence.