Even in highly disciplined Singapore, home of the most sophisticated road-pricing system in the world, citizens have had to be cajoled into accepting the latest flexible charging system with reductions on other motor taxes.

ECONOMIST: Road pricing

"We've got two policies, the first in terms of a national system of road pricing is that we have a debate ahead of a decision which lies some years away, " Mr Alexander said.

BBC: NEWS | UK | UK Politics | PM denies road toll 'stealth tax'

In Britain, such a system is being introduced as part of a road-pricing scheme for lorries on some motorways.

ECONOMIST: Clean machine