Don't forget though the money you buy the tax with has already been taxed (and national insurance deducted) for most people, then the fuel you buy with money that has already been taxed, carries a lot of tax itself. Plus the car itself when first purchased included vat, on money that has already Ben taxed, then you have to pay road tax plus first registration tax.
This country is run by thieves. No wonder they go so lightly on criminals.