Motorway tolls would add substantially to fleet running costs, compounding the inflationary impact of urban congestion charging due for implementation in London and other cities next year.
A recent report by the independent Commission for Integrated Transport suggested that motorists could pay to use roads on a mile-by-mile basis, although Stephen Byers, secretary of state at the Department of Transport, Local Government and the Regions (DTLR), insisted the Government had no intention of introducing road-user charging.
However, the DTLR has commissioned an independent study into road tolls, published on the day of the Queen Mother's funeral.
This led to Opposition accusations that the Government was trying to 'bury' bad news, a claim denied by the DTLR that also insisted the report's conclusions do not necessarily reflect the opinion of Government.
However, the fact that the DTLR commissioned consultants to review the potential impact of tolls on motorways such as the M1, M6 and M25 shows that road charging remains a potential solution to the gridlock that paralyses much of the UK's road network.
In their report, the consultants make it clear that road tolling may ease congestion on motorways, but would have disastrous consequences elsewhere, driving traffic onto other roads where it would increase congestion and lead to a rise in accident rates.
The report says, for example, that tolls on the M1, would lead to 'a 30%-plus diversion of traffic off the M1, mostly to non-motorway roads, with a very small (0.5%) additional shift to public transport'.
'This had the effect of significantly increasing congestion on other roads and lead to a significant predicted increase in road traffic accidents,' the report continues.
While reducing traffic volumes on the M1 by 30%-plus would have a positive impact for drivers in terms both of driving times and lower accident rates, the report added that 'diversion of trips off the motorway due to tolling leads to an increase in average journey times and distance'.
In the study of the A1 through Yorkshire, the consultants found that 50% of the traffic in congested sections were cars used for journeys to and from work, and that 50% of commuters travel more than 30 miles each way, with no alternative way of getting to work.
'For many of these car commuters to use the current public transport system, they would incur substantial wait times for infrequent services and would have to interchange between services to a degree likely to be regarded as unacceptable,' said the report.
It added that the rail system is overloaded and could not carry the car commuters without capacity enhancements.
But the consultants reject the idea of expanding the road network to deal with congestion, claiming this would simply lead to more long distance car trips.
Instead, they suggest that charging drivers 20 pence per kilometre for urban driving, and 2p/km on motorways would substantially reduce motorway traffic volumes and increase traffic speeds, thereby benefiting business efficiency and the economy - and yielding large revenues to the Treasury.
However, the report concluded: 'The policy most effective in terms of reducing flows on the motorways and A1 was a substantial increase in fuel price (10p/km).'
The essential nature of business journeys for employees and goods deliveries have made fleets a target market for the operators of tolled roads who promise lower traffic volumes and faster, more predictable journey times.
Midland Expressway, which holds the concession to build the Birmingham North Relief Road, or M6 Toll, views corporate clients as the ideal customers for the country's first pay-on-use motorway.
Steven Boffey, head of marketing for Midland Expressway, said: 'The M6 Toll is promising to cut around 40 minutes off rush hour journey times when compared to the same journey on the existing M6.
'My job is to convince people that it will be money very well spent, in terms of time, reduced stress and, for businesses, increased profits.'