Londoners are to be asked for their opinions in a review of the level of parking fines.
The current average parking fine in London is £100
The Association of London Government (ALG) is starting a consultation for reassessing the penalties, which could see them increase from £100 to £120.
A spokesman for the ALG said the three-month consultation, which begins in June, could also see fines go down.
The ALG is also looking at varying the tariffs depending on the seriousness of the offence.
Average parking fines in London amount to £100, but this drops to £50 if paid within two weeks.
The ALG also wants to hear views about a sliding scale of fines.
Under its proposal, a motorist overstaying in a parking bay would be fined £90 but someone parked on double yellow lines would face a bill of £110.
Edmund King, of the RAC, said: "In principle, the sliding scale could be a fairer system.
"But I don't think we need to increase fines to £120, unless it is for really dangerous parking, like parking on a junction or on the jagged lines by pedestrian crossings.
"Otherwise it is just about raising revenue and not about keeping the traffic flowing."
Nick Lester, from the ALG, said: "There are no specific proposals to raise the fines at all.
"What we are doing is consulting Londoners and other organisations representing drivers, about how we should come out of the review on penalties, which we have to do every four years.
"The options are very wide open. There could be no increase, and it could be an increase on a different number of levels. It could even go down."
A final decision on the levels of the fines will be made at the end of the year.