Joshua Aaron Byrne, of Ashmont, and Matthew Thomas Cahill, of Batlow, were both sentenced to 10 years and six months imprisonment, including a non-parole period of seven years, in May last year after pleading guilty to manslaughter.

Craig Smith, aged 53, died when a VE Commodore driven by Byrne ploughed into his vehicle on Coleman Street in Turvey Park on October 23, 2017.

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Byrne and Cahill were racing each other at speeds of up to 140 kilometres per hour on Coleman Street, before Byrne's Holden Commodore crossed onto the wrong side of the road and smashed into Mr Smith's ute.

At the time, Mr Smith had been making a legal u-turn outside his office and was not involved in the race.

The Court of Criminal Appeal at the NSW Supreme Court held a hearing into the sentences on June 30 following complaints that the jail terms imposed were "manifestly excessive".

Byrne, aged 22 at the time of sentencing and Cahill, then aged 20, submitted to the Court of Criminal Appeal that they should have their sentences reduced because of their youth at the time of the offending.

They both submitted that their sentences were excessive compared to similar cases of manslaughter resulting from the negligent use of a motor vehicle.

The president of the Court of Appeal, Justice Andrew Bell, and justices Stephen Rothman and Richard Button handed down their decision on Wednesday.

All three justices agreed to uphold the sentences imposed by Wagga District Court Judge Gordon Lerve.

"In my opinion, the sentences imposed were stern, but not manifestly excessive," Justice Button said.

In the appeal decision, Justice Bell said the fact Byrne and Cahill were on provisional driver's licences at the time "only exacerbated the culpability of the offending and made deterrence a particularly important consideration in the sentencing".

"Cases of this kind are a tragedy, pre-eminently for the family of the wholly innocent deceased whose lives have been irretrievably affected by the reckless and irresponsible conduct of the offenders," he said.

"But they are also a tragedy for the offenders themselves and their families whose lives will also be irretrievably affected.

"The tragedy could easily have been multiplied given the location of the 'race', the speed at which both vehicles travelled and the number of passengers in each vehicle.

"It is fortunate that further tragedy did not eventuate."

On the day of the crash, Byrne and Cahill were attending TAFE for an automotive course and during a morning break in lessons, both men drove to a nearby cafe with two fellow students in each of their cars.

A court hearing in Wagga last year was told there was no evidence the race had been pre-planned by the two drivers.

Byrne and Cahill pulled up alongside each other at the traffic lights at the intersection of Edmondson and Coleman streets and "accelerated aggressively through the intersection and commenced a street race" when the lights turned green, according to a statement of agreed facts.

Mr Smith was preforming a safe and legal u-turn when the driver's side of his ute was struck by Byrne's Commodore with such force it almost detached the tray from the cabin.

Mr Smith was killed instantly in the collision, while Byrne sustained lacerations to his hands and one of his passengers was trapped in the Commodore.

"The message must be sent in unequivocal terms that motor vehicles are not playthings or dodgem cars to be raced by young people for fun or thrills and with impunity. They are to be used responsibly and strictly in accordance with the rules of the road," Justice Bell said.

"These rules exist not only for the safety of the drivers and passengers themselves, but for pedestrians and other road users.

"The holding of a driver's licence conferring the right to drive a motor vehicle is a privilege which carries heavy responsibilities. Those responsibilities were flagrantly cast aside in the current case and the sentences imposed, though heavy, were appropriate in the circumstances and certainly not manifestly excessive."

Byrne and Cahill had submitted their case did not involve factors that would increase the severity of the offending, such as unlicensed driving, drug or alcohol use, prolonged periods of dangerous driving or police pursuits.

Byrne submitted his diagnosis of adult ADHD was also grounds for a reduced sentence.

Both men will be eligible for parole in 2026.