Israr Muhammed, 41, lost control of his 16-year-old Honda Civic as he and another driver, Adam Molloy, drove "like idiots" in the outside lane of the M62 in East Yorkshire in July 2018.
Muhammed's son, Say Han Ali, suffered catastrophic head injuries after the car spun across all three lanes of the motorway and hit a tree on an embankment.
His wife Safeena Ali and daughter, who was 11 at the time, also suffered serious injuries.
Sentencing Muhammed and 29-year-old Molloy at Hull Crown Court, Judge David Tremberg said Muhammed had been seen driving "in an erratic and unsafe manner" for many miles before the accident, failing to give way at a roundabout and weaving in and out of traffic.
He said Muhammed claimed Molloy - who worked as an HGV driver - began "tailgating" him.
Judge Tremberg said: "Expert assessment of the footage reveals that each of you was travelling in excess of 100mph and there were roughly 10 metres between your cars as you sped along.
"Other drivers formed the impression that you were racing and driving like idiots.
"I'm satisfied that you, Israr Muhammed, had a whole array of safe choices you could have made to avoid rising to the bait.
"Nobody forced you to exceed the speed limit, nobody could have done, nobody forced you to stay pig-headedly in the outside lane of the motorway because the middle lane was clear for a long stretch.
"You, Adam Molloy, elected not to give evidence at the trial. That's not surprising because no-one was forcing you to drive as you did and you could not have had an answer to why you were driving in such an aggressive and intimidating fashion at such a high speed and so close to the car ahead.
"The fact that you hold an HGV licence makes your incredibly foolhardy and gratuitous behaviour even more mystifying."
Afterwards Sergeant Rob Mazingham of Humberside Police's Serious Collisions Unit said: “The car that Israr Muhammed was driving was not roadworthy, its rear tyre was 16 years old and defective and the resulting blow-out caused the series of events that led to the death of his three-year-old son and the serious, life changing injuries of his wife and second child. In addition the car seat containing Israr was not secured in any way to the vehicle and offered him no protection when the collision occurred.
“I have been involved in many road traffic collisions however the death of a child in such awful circumstances can only be described as a tragic loss of life.
“We work tirelessly in trying to stop people exceeding the speed limit and to take un-roadworthy vehicles off the road, not only for your safety but that of others in your car and other road users. I would urge all vehicle owners to carry out the regular basic checks before driving and to ensure that all passengers, particularly children are correctly strapped in and secure.
"The conviction of Adam Molloy should serve as a serious reminder that to engage in racing or competitive driving, regardless of whether a collision occurs, can result in a custodial sentence.
“I am sure that Israr Muhammed and Adam Molloy will now spend their time in prison with the memory of that fateful day and the decisions they took that led to such a tragic outcome.”
Muhammed, from Batley, West Yorkshire, was found guilty of causing death by dangerous driving, two counts of causing serious injury by dangerous driving, and one count of causing death while uninsured.
Molloy, of Normanton, West Yorkshire, was also jailed for four and a half years after being convicted at a trial last month of causing death by dangerous driving and two counts of causing serious injury by dangerous driving.