Closing the M4 bus lane has saved drivers one minute on journey times, Government figures suggest.
The dedicated eastbound lane was launched in 1999 by Labour's Transport Secretary, John Prescott. But the Coalition promised to scrap the three-and-a-half-mile lane into London, which could only be used by buses, black cabs and motorbikes.
Speaking last year, the then Transport Secretary, Philip Hammond, called the lane symbolic of Labour's "war on the motorist" while Top Gear presenter Jeremy Clarkson dismissed it as "idiotic".
Transport minister Mike Penning said: "Interim findings suggest there is an overall journey time saving in the order of 60 seconds for drivers travelling eastbound on the M4 between junction four for Heathrow Airport and junction one, where the M4 terminates into the A4. Further detailed analysis and data collection is being carried out to complete a full year's review."
Answering a question from Labour MP John Woodcock, Mr Penning said the Highways Agency hopes to report early next year.