The construction and maintenance of highways and roads is a terribly expensive proposition, especially in the climate that we have in St. Petersburg. Logic and fairness demand that the cost of roadbuilding should be borne by those who use the roads.
The income of the St. Petersburg terretorial road fund in 2002 was 6 billion rubles, almost 5 thousand rubles for every car in the city. But of that sum, only 400 million was paid by the car owners (about 300 rubles per car). It turns out that more than 90% of the road fund is subsidized by general taxes. In other words, an enormous hidden subsidy for private car owners.
To increase the tax on car owners to 5000 rubles per year would be unfair, because many drivers rarely use their cars (for example only summer to and from their dacha), while others are constantly driving around the city. The only fair road tax is the gas tax, because the use of gasoline exactly corresponds to the use of roads.
In the West the gas tax is called an "eco tax" because it leads to the reduction in the use of private auto transport. This tax not only finances their roads, but provides subsidies for mass transit and other social needs.