This may soon change. The Spanish Ministry of Economy is readying legislation to instruct municipalities to impose a road tax based on "environmental parameters," that is, CO2 emissions. The more a car pollutes, the more taxes its driver will pay per year. The current tax rate is based on an old system that uses engine displacement and power. The reform will also require the owner of the car to pay taxes where he or she lives. Some companies have been registering cars in smaller municipalities with reduced car taxes to shave costs. Some cities such as Zaragoza and Barcelona already offer discounts on this tax for hybrid and electric cars.
[Source: El País]