In the UK, the so-called car tax is an emissions tax (i.e. electric vehicles pay £0) and doesn't pay for road maintenance etc. Roads are paid for out of general taxation (e.g. income tax). Actual road tax ended in 1937.

I feel this is worth correcting as "don't bloody pay road tax" is a common form of abuse aimed at cyclists which is wrong on a number of levels. A lot of cyclists also drive a car and non-driving cyclists would fund roads if they pay tax. Another way to think about it is that the emissions tax for cycles would be zero anyway.