Chris and Sue Moores's son Wayne died when his motorbike was struck by a drink driver in 2010.
The couple spoke out in response to consultation on proposed reform of sentencing for driving offences.
They believe increased sentences should be backed up by manslaughter charges.
Mr Moores, 28, was killed by a Vauxhall Astra driven by Donna Hackett on the M4 near Swindon.
Hackett, then aged 26, fled and was found by police asleep in a ditch. She served half of a six-year jail term after she was found guilty of causing death by careless driving while drunk.
The Ministry of Justice consultation suggests offenders who cause death by careless driving while under the influence of drink or drugs could soon be handed a life sentence - an increase on the current 14-year upper limit.
Source: Crown Prosecution Service
But Mr and Mrs Moores, from Chandlers Ford, Hampshire, also want the offence to be upgraded to a charge of manslaughter.
Mr Moores said: "Somebody can drive drunk and kill my son. Why is that not manslaughter?
"Nothing can prepare a parent for seeing their child in the mortuary. That will stay with me every day, every day that vision comes into my mind.
"Our life is ruined."
Mrs Moores added: "There's nothing careless about drink driving. I don't want anybody else to feel like us."
Ms Hackett, who lived in Radnor Street, Swindon, at the time of the offence, appealed against her sentence in September 2011, but was refused.
A Ministry of Justice spokesperson said: "We are determined to make sure those who kill whilst driving under the influence of alcohol or drugs face the full force of the law.
"That is why we are consulting on plans that will see the maximum sentence for a number of offences in this area increase from 14 years to life."
A response to the Ministry of Justice consultation, which closes on 1 February, is due to be published by May.
A proposal to introduce life sentences for the offence of careless driving while under the influence of drink or drugs does not go far enough, according to the parents of one victim.