1. All European countries tax gasoline far more heavily than the US, usually to the tune of 100-200% of the wholesale price. That is an intentional policy to lower gasoline consumption, governments could easily remove it if they wished for more energy consumption.

2. Not all European countries are "poorer" than the US even by a GDP measure. Norway which is a petrostate has about half the energy consumption of the US (measured by per capita carbon emissions), Switzerland about a quarter! If anything richer countries in Europe are better than the poorer Eastern neighbour as well as better than the US in minimizing energy waste -- better-insulated housing, better rail and subway networks.