Duncan and Emma Woods will forever be haunted by the final moments they spent with their young son.

But the devastated couple refuse to be burdened with anger towards the person who took Nayan Woods, 4, from them.

They have forgiven Ashley David Austin, 18, for killing Nayan when he lost control of his illegally modified car and mounted a footpath in Christchurch in May.

They asked that he not be sent to jail - and Judge Phillip Moran yesterday heeded their wishes. Austin will instead serve a sentence of six months' community detention with a weekend curfew and 200 hours of community work, in addition to being banned from driving for three years.

Judge Moran said Austin was "clearly a young man of good character" who made a dreadful mistake.

Austin, sobbing uncontrollably after emerging from the Christchurch District Court, was embraced by Mrs Woods.

"It's easy to raise voices in anger and condemn others for their mistakes," Mrs Woods said.

"Unfortunately, human nature means mistakes are often made. Although the effects of this mistake cannot be undone or made right, we recognise that Ash has done everything he can to support us. We do not believe he can be punished any more severely than by having the guilt of this accident on his conscience."

Mr Woods told Austin to "honour the spirit of my boy".

"I want you to make a positive impact on all those others in the community in which you live. Nayan would have. You owe it to him."

Austin was too upset to read his own written statement outside court, but in it he thanked the Woods for their empathy and compassion.

"It has been an honour to spend time with Emma and Duncan and to learn about Nayan.

"I know that no apology or action can take away the loss, hurt and suffering I have caused. But I am truly sorry."

The court yesterday heard about the harrowing effects of the accident on the Woods family.

Mrs Woods and son Jacob, 6, were also injured when they were hit by Austin's car as they were walking home with Nayan.

"I will always remember the last thing Nayan asked me was if I could carry him," Mrs Woods said.

"I carried him most places, but lately was trying to get him to walk more. I said no, because I was carrying groceries and we were almost home. I will always wonder why I didn't pick him up, and what would have happened if I had."

Mr Woods' last moments with Nayan involved taking a computer from him so he could catch an early bus to work.

"His last interaction with me left him in tears, refusing to speak to me. I told him I loved him, as I did every day when I went to work. He, along with Jacob, would often wave to me from the window - on that day they never appeared. I can only guess it was because they were still upset with me leaving. I never saw [Nayan] alive again. I will never get the chance to hold him, talk with him, and play with him again. I'm tortured by this, and would give anything to have taken the next bus that day. At least I would have known his last time with me was happy."