Hundreds of motorists are daily breaking the law by using a lane reserved for park and ride drivers.
The lane, from Oxford's Botley interchange to the Seacourt park and ride, is reserved for motorists intending to use the bus service to the city centre.
But many drivers take an illegal short cut to avoid the queues and traffic lights.
Police and highways officials said it was difficult to prevent the practice which angers law-abiding drivers, delays real users of the park and ride service and causes a nuisance to businesses.
In a one-hour survey, the Oxford Mail counted 187 cars and vans illegally using the lane. Many drivers turned off Botley Road, went round the roundabout on the park and ride site, and then returned to the main stream of traffic.
Other vehicles turned in the car park entrance or on the forecourt of the Mitsubishi garage opposite.
Others simply pushed in to the traffic from the bus lane.
County council officials said they were surprised by the extent of the abuse.
Noel Newson, a group manager in the environmental services department, said: "What has obviously happened is that drivers have seen others doing it and decided to join in."
Insp Keith Henderson, of Oxford police, said: "This is a designated bus lane. People driving in it but not intending to use the park and ride are liable for a fixed penalty fine."
Police action was welcomed by Richard Shepherd, the dealer principal of Motorworld.
He said: "Sometimes there are cars completely blocking our access. They are also turning on the forecourt on the Mitsubishi side. Drivers are most abusive when they are challenged."
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