BBC News, London
The M4 bus lane was created by John Prescott
The M4 bus lane is hardly being enforced - with only a handful of penalty notices issued to drivers who wrongly use the lane each year.
BBC London has learned that just 14 £60 fixed penalty notices were issued in 2008 with just six so far this year.
Minicab company Addison Lee - which is not allowed to drive in the lane - has now told its drivers to use it.
The 3.5 mile lane on the motorway into west London was launched by then-Deputy Prime Minister John Prescott in 1999.
But there are no dedicated cameras watching the bus lane - and the Metropolitan Police have said policing it is not a priority.
A spokeswoman said: "The Met is constantly balancing our aim to improve safety on London's roads with making the most effective use of road policing resources.
"While officers will enforce non-criminal road traffic offences wherever possible, we will always prioritise resources for activity that can reduce casualties."
Steve McNamara, of the Licensed Taxi Drivers Association, said: "It's absolutely farcical. We've got a bus lane that no-one enforces - what is the point in having it?
"The world and his mother is using it. It's supposed to be a bus lane - it's anything but, and soon it will be too congested for buses to use."
He added: "It's actually very dangerous. You can be going down the bus lane at 50mph and someone pulls out from stationary on the inside.
"I've seen untold near misses and it's only a matter of time before someone gets killed - all a matter of lack of enforcement."
Only buses, coaches, motorbikes, emergency vehicles and licensed taxis can use the lane, which runs between Heathrow airport and central London.
Journey times improved for all types of traffic in the first three months of the £1.9m lane, according to Transport Research Laboratory figures.
But Edmund King, AA president, said: "At times the M4 bus lane seem like an M4 ghost lane - it is under-used and under-policed.
"Currently it is a white elephant.
"If we can't find ways to make it more efficient perhaps it should be opened to all."
A Highways Agency spokesman said: "Apart from emergency service vehicles, the only other vehicles allowed to use the lane are buses, licensed taxis and motorcycles. Private hire vehicles are not allowed."