In a report published today, the RAC foundation outlined millions of pounds of parking penalties could have been charged illegally on private land across the England and Wales.
The foundation has asked for the argument to be tested in court and has urged the government to ensure extra car parking charges are reasonable and enforceable.
Experts believe overcharging in private parking penalties may have reached £100 million in 2013 alone, leaving millions of motorists in line for parking refunds.
Barrister John De Waal QC conducted a study for the foundation and found the sums handed over in fines by drivers often exceed any recompense for any genuine loss.
Stephen Glaister, RAC Foundation director, said: “We would like to see this legal argument tested in a higher court so that a binding precedent is set.
“At the same time we would like the government to do what it should have done at the outset and set out what are reasonable charges.”
He continued: “Ministers thought that the ban on clamping would end parking problems on private land. As we warned at the time, they were wrong.
“They allowed a system of ticketing to emerge which is barely regulated. In effect drivers have been short-changed.”