How effective would Subsidies be when given to Public Transport?

-The Purpose of the Subsidy is to Reduce Car Usage + Pollution Levels -Subsidies don't always Equal Increases in Passengers, as Bus and Rail Transport may be seen as Inferior Goods. Furthermore Travelling by Car may be Easier and Private -Allocation of Resources to Public Transport Sectors which doesn't Increase their Usage (And therefore Decrease in Pollution) can be seen as a Net Welfare Loss