Motorists using two of Oxford's park-and-ride sites will have to pay if they want to leave their cars for more than 11 hours under new proposals.
The county council plans to introduce charges at the two sites it controls, Thornhill and Water Eaton.
It expects to make about £150,000 a year from the changes.
Drivers staying for between 11 and 24 hours will pay £3 with an addition £3 charge for each subsequent 24 period to a maximum of 72 hours.
The city council run park-and-ride sites of Peartree, Seacourt and Redbridge all currently charge £1.50 a day or £7.50 for seven days.
Oxfordshire County Council's deputy leader Rodney Rose said: "We want to safeguard the future of the county council's park-and-ride sites and this is something we have committed to doing for some time now.
"We've looked into this in some detail and think the 11-hour limit on free parking is about right, allowing for a normal working day with a fair bit of leeway either side.
"We obviously have to set the bar somewhere but we want to hear people's views on this as well as the other proposals."
The park-and-rides affected are often used by people travelling to London on buses which leave from the site.