Taxes related to the ownership and usage of vehicles were introduced in most OECD countries in the first half of the 20th century and have become an important source of tax revenue for many governments. All member countries rely on a range of tax instruments to ensure significant revenue from both private and commercial vehicle owners and road users. Vehicle and vehicle usage taxation in its widest definition represents a prime example of the use of the whole spectrum of consumption taxes for taxing vehicles and their use, including VAT as well as ad quantum or ad valorem taxes (see definitions in Chapter 3). These taxes have progressively been adapted to influence consumer behaviour and curb transport externalities, in particular environmental externalities.