Transport ministers have been attacked for not doing enough to ease traffic congestion in England's suburbs.
More drivers are making short trips on major roads, said the ITC
The Independent Transport Commission
(ITC) warned of an increase in journey-to-work times in coming years.
Without congestion charging in the suburbs, commuting times could rise 10 minutes on average by 2021, it said.
Land use and transport policies tailored to the suburbs were needed urgently, ITC chairman, Sir Patrick Brown, said in a report.
Suburban dwellers account for 29m of England's population and use cars for 64% of all journeys, the report found.
It said commuting today was quicker in the suburbs than in cities.
But suburbanites face lengthening delays as existing bypasses and motorways, such as the M62 and M25, fill up with drivers making short-distance inter-suburban trips.
Journey-to-work times are forecast to rise from the current average of 25 minutes to 35 minutes by 2021, said the study.
The report said the enormous economic importance of the suburbs had been neglected.
Sir Patrick added: "Governments have concentrated on improving access to city centres and on long-distance inter-city road and rail routes."
After driving, walking is the next most popular mode of travel in the suburbs, with buses and trains used
for only 8% of journeys.
The average suburbanite travels 6,531 miles a year, according to the ITC's study.
In 2001, around 25% of suburban households had no car compared with 47% without cars in urban areas.
A transport department spokeswoman told BBC News Online the department would respond in full once it had given the report the consideration it needed.