Also just suppose that the road tax bands based on CO2 are scrapped and replaced with something that is a composite of total pollution footprint.
If the tax bands are to be based on CO2 emissions (or a total pollution footprint) they should take mileage into account.
Scrap the current scheme, add an arbitrary amount onto the price at the petrol pumps. Means a fairer scheme where everyone pays for what they 'pollute' and the added benefit that nobody could avoid paying road tax.