A study by academics found that 600km of new roads would be needed each year, about the average achieved in the 1990s.
Public transport is not a solution because cars carry 86 per cent of passenger traffic and 65 per cent of freight moves by road, the report claims. Emissions would rise by only five per cent as freer-flowing traffic would reduce carbon output, it adds.
Author Stephen Glaister of Imperial College London said: "As long as motorists pay, it is fine to build more roads." Road pricing would raise £30 billion a year while road building would cost £4.5 billion, the report says. Using the surplus to cut road tax would make pricing more acceptable, it suggests.
Campaign for Better Transport roads and climate campaigner Rebecca Lush Blum said: "This is a recipe for a polluted, obese nation."
Roads and Reality is available at PlanningResource.co.uk/doc.
