Mean fuel duty costs versus mean road pricing costs for a range of scenarios, vehicle-owning households. Per-mile road charge set at a rate that raises the same amount of revenue as fuel duty does at present. Free mileage is on a per vehicle basis. Modelling the distributional impact of road pricing: Social Market Foundation modelling shown in Chart 1 shows that a road pricing regime with a uniform per mile charge and a free mileage allowance per vehicle would be slightly financially beneficial to lower income motorists, compared with the current fuel duty regime. For example, a revenue-neutral regime with a free allowance of 2,500 miles would leave motorist households in the bottom two income quintiles about £20 per year better off than the current fuel duty regime. This amounting to about £92m in aggregate. This rises to about £40 per year with a free allowance of 5,000 miles - £188m in aggregate.