Reducing the frequency of MOT tests for cars would be "nonsensical and inhumane", and could lead to more than 250 additional deaths each year, campaigners have said.
Government proposals to relax the current rules, under which an MOT is required annually for cars three years old or more, have been slammed by road safety, motoring and industry groups.
The Government has suggested the system be downgraded to require MOT tests less frequently, but 25 organisations have joined together to campaign against the changes.
As well as risking more deaths, campaigners fear the changes could lead to 2,200 additional serious injuries a year.
Julie Townsend, deputy chief executive of road safety charity Brake, said: "Downgrading the system so MOTs are only required every two years is a nonsensical and inhumane policy that would mean many more needless tragedies."
The financial impact of the changes is also a source of concern for campaigners, who say they will result in more expensive repairs and higher car insurance bills for motorists.
© Press Association 2011