London's congestion charging scheme has reduced traffic by more than expected and caused none of the chaos which critics feared.
Traffic in the zone has dropped since the charge started
The £5 charge to drive into central London has reduced traffic by 17%, speeded up bus services and brought more customers into shops which have congestion charging paypoints, says the man in charge of the two-month-old project, Transport for London managing director Derek Turner.
After decades of gridlock in central London, vehicle speeds have increased "dramatically", though this is causing some concern about road safety.
But it will not spread far in Britain.
Despite the apparent success of the London scheme, it seems few other cities are likely to introduce congestion charging.
Only Edinburgh and Bristol are working seriously on their own schemes.
A lack of take-up will undermine the government's plans for congestion charging to be a vital tool for reducing traffic in cities, and for raising extra money for public transport improvements.
Experts say there are a number of reasons.
They say there is less congestion outside London, reducing the justification for charging.
London congestion charge
100,000 drivers per day paying £5 charge
3,000 drivers per day being fined £80 for evasion
Bicycle, scooter and motorbike commuters up 20%
Bus use in morning rush hour up 14%
Bus speeds up 20%
Annual revenue expected to be £100m (£130m predicted)
Few local politicians are brave enough to follow London mayor Ken Livingstone's lead in championing such projects.
Most cities do not have big enough bus and train networks to provide sufficient public transport alternatives for car drivers.
Only London has a single body in overall charge of transport.
Other cities will suffer from differences between neighbouring local authorities.
Only London has regulated bus services.
Other cities have no legal powers to coordinate services as part of a congestion charging scheme.
Experts believe the obstacles are so great none of the other cities which have expressed interest in congestion charging - including Leeds, Glasgow, Newcastle, York, Sheffield, Liverpool, Birmingham, Oxford and Cardiff - are actually likely to go ahead with their own schemes.
But the record of congestion charging in London so far has quickly attracted the interested of cities around the world.
There is no evidence of more accidents since the scheme began
The scheme here is far larger and more complex than in the few other cities which also have charging, such as Singapore, Oslo and Melbourne.
Engineers behind the London scheme say New York, Dublin and Milan are particularly keen to follow London's lead.
Other European cities said to be interested include Madrid, Barcelona, Valencia, Rome, Berlin and Istanbul; while in the US there is enthusiasm in Boston, Pittsburg and Philadelphia.
However, just as in Britain, experts say there will be talk in many cities, but action in only a few.