The Automobile Association says claims changes to the warrant of fitness system will result in dozens of extra deaths on the roads are scaremongering.
The Government is proposing to require warrant-of-fitness checks once a year, rather than six-monthly, for cars under 12 years old.
A group campaigning against the changes - including the Motor Trade Association (MTA) - says the Government is ignoring crucial international research that indicates the move would lead to an extra 80 deaths each year.
Veteran V8 supercars driver Greg Murphy, who fronts MTA advertisements, says if the changes go ahead the Government will face harsh repercussions.
Mr Murphy says the system should not be changed, because a check twice a year is how people know that their cars are safe.
But a spokesperson for the Automobile Association says the group is making false claims to stop the changes because their businesses will lose money if they go ahead.
Mark Stockdale says the Government is not putting forward any options that will compromise road safety and the claims are just scaremongering.
The editor of a car buyers' guide, Clive Mathew-Wilson, says the system needs to be simplified to accommodate people on low incomes.