Radical plans that would result in car drivers charged for using motorways and trunk roads while fuel duties and vehicle excise duties are cut have been unveiled by Nick Clegg, the leader of the Liberal Democrats.

Radical plans that would result in car drivers charged for using motorways and trunk roads while fuel duties and vehicle excise duties are cut have been unveiled by Nick Clegg, the leader of the Liberal Democrats.

Under the LibDem transport plans the most polluting, high-consumption cars would be hit by a "showroom" tax of up to £2000 and road charging would be introduced at 8p a kilometre for motorways and trunk roads.

That could rise to around 12p for cars pumping out the most greenhouse gas emissions, although the most efficient vehicles would pay nothing. The proposals form part of a long-term transport strategy that the LibDems claim every other party is running scared from, and include surcharges on domestic flights to fund investment in rail.

In a sign of the aspiration of the Future Transport Fund the LibDems want to establish, Mr Clegg said their plans would lead to a rail renaissance that "would undo some of what Beeching did in the 1960s" when many branch lines were closed down.

The plans would be revenue neutral Mr Clegg said, but in a move that will anger hauliers - the LibDems propose an immediate road user charge for lorries rising according to how much fuel they consume. This would be applied to all roads, not just trunks and motorways, and foreign registered lorries would have to pay the charge before leaving the UK. Lorry drivers are already complaining that the haulage industry is being crippled by high tax on fuel.

In Scotland, responsibility for the trunk road network rests with the devolved government, but the LibDems insisted that their taxation plans would apply across the whole of the UK. "You've got to be able to charge motorists the same across the UK otherwise it would be unfair and we think we can reach an accommodation on that point," said Norman Baker, the LibDem environment spokesman.

He also set out proposals to introduce a surcharge on domestic flights, raising £500m per year, to fund substantial improvements and the electrification of the rail system.

Mr Baker said "lifeline" flights such as those to and from Aberdeen, Inverness and the Scottish islands would not face higher taxes. "Flights to Glasgow and Edinburgh from London will be taxed," he said. "People will be encouraged to take the train."

The proposals were launched while Gordon Brown comes under pressure over a retrospective hike in vehicle excise duty expected to hit millions of motorists. From next year VED will cost £440 for vehicles in the top bracket.

Mr Clegg said his own plans for higher VED rates would only be a temporary measure until the tax was abolished altogether up to 10 years into a LibDem administration. At that point, fuel duty would be cut as well and the road charging scheme would be introduced.

On rail, the LibDems said that the contracts given to train operating companies should be awarded over much longer periods, so that the companies have more incentive to invest long term and re-open branch lines. The party is planning for full electrification of the rail network by 2050.

Mr Baker said: "Labour's 30-year plan for the railways stops inexplicably in 2014 and there are no firm proposals from the Conservatives.

"We are the only party with concrete proposals to build a transport system fit for the 21st century."