Four in ten appeals made to councils over parking and bus lane fines were successful, it is reported.
Figures obtained through the Freedom of Information Act by the BBC show that 1.8 million of the almost 4.3 million appeals made over the last five years were successful.
The data also showed that 84 councils accepted more than 50% of appeals - with the RAC saying councils should rectify the problems which lead to motorists being punished by mistake.
Spokesman Simon Williams said the figures were "frightening", but Martin Tett, transport spokesman for the Local Government Association, told the BBC the figures suggest the appeals process is working.
He said: "As these figures confirm, people who want to challenge a parking fine have access to a clear and effective appeals process.
"Councils have to strike a difficult balance when setting parking policy, to make sure that there are spaces available for residents, high streets are kept vibrant and traffic is kept moving.
"They also need to ensure that emergency vehicles can get access to incidents quickly."