A new parking system heralded as a "fairer deal" for London's motorists resulted in councils issuing an extra £40m in tickets in one year alone.
Under London's two-tier system some fines are set at £80 and "more serious" offences - such as parking on a single yellow line - result in a £120 charge.
But councils issued three times more fines at the higher level than the lower, BBC London has learned.
London Councils, who spearheaded the scheme, said they had public backing.
When it was introduced in July 2007 the two-tier system was praised by dozens of councils.
Councillor Nigel Haselden, of Lambeth Council, said at the time: "We welcome London Councils' decision to introduce differential penalties for parking.
"It is consistent with our move to have a fair parking system."
But in 2007-2008 nearly three million fines set at £120 were issued by London boroughs.
That compares to 900,000 fines issued at £80.
The total value of the tickets issued was £40m higher than it would have been under the old tariff with a flat £50 penalty.
However the extra amount councils actually received is likely to have been less because a 50% discount is offered if tickets are paid within 14 days.
Critics describe it as a "cynical" scheme intended to increase parking revenue while appearing to be fairer on motorists.
Parking campaigner Barrie Segal said: "At the launch they were saying this would be a fairer system for motorists.
"But it actually gave them the chance to substantially increase the fine for every day offences such as stopping on a single yellow line."
Mr Segal added: "There was definitely an element of cynicism in this.
"I would challenge them to prove they did not make projections at the time showing this system would raise revenue."
Islington-based taxi driver Joe Cartwright said: "It is an obvious PR stunt.
"They want to make themselves look better while making as much money as possible from the motorist."
The two-tier system was named 'Most Innovative Transport Project' at the 2008 Transport Awards.
A London Councils spokeswoman said: "People told us during a consultation that motorists who selfishly endanger lives, for example parking on a double yellow, should receive a heavier penalty.
"It is only right that enforcement is structured this way."