Motorists in the South East need convincing over government plans to deal with congestion using road pricing, said a leading think tank.
The M25 between Reigate and Dartford is the worst for congestion
In a report by the Institute for Public Policy Research (IPPR) drivers said they were fed up with not knowing how long a journey would take.
The government said road pricing has a major part to play in the future.
Traffic in the South East is predicted to increase by more than 30% over the next 20 years.
The government spokesperson said: "We are determined to work with drivers to find the solution this country needs."
A report by the Department for Transport published in February said the region had the most congested stretch of road in England - the M25 between Reigate in Surrey and the Dartford Thames river crossing in Kent.
IPPR senior research fellow, Anthony Vigor, said: "Motorists are unable to predict how long their journeys will take.
"National road pricing would be an effective way to tackle congestion.
"But the public are sceptical and unsure how such a scheme would work."
The Department for Transport added: "No-one knows better than drivers that congestion is a real long-term problem."
The government is working with local authorities to develop a major pilot for the scheme in the next 4-5 years.
The IPPR said a national road pricing scheme could raise about £10bn which could replace road tax and pay for public transport improvements.
It said motorists could be charged as much as £1 per mile at peak times on the most congested sections of motorways.